27620 is a product of a power of 2 and two 4k+1 primes and so it can be expressed as a sum.of two squares in two different ways viz. 8^2+166^2 and 106^2+128^2.

27620 is a member of OEIS A352332: numbers k s.t. k = phi(k') + phi(k''), where phi is Euler totient function, k' is arithmetic derivative of k and k'' is second arithmetic derivative of k.

The sequence can be generated as follows:

INPUT

# Numbers k for which k = phi(k') + phi(k'')

L=[]

for number in [2..40000]:

  # First Arithmetic Derivative

  n=number

  total1=0

  F1=list(factor(n))

  for f in F1:

    total1+=f[1]/f[0]

  total1=total1*n

  # End First Arithmetic Derivative

   # First Arithmetic Derivative

  n=total1

  total2=0

  F2=list(factor(n))

  for f in F2:

    total2+=f[1]/f[0]

  total2=total2*n

  # End First Arithmetic Derivative

  # Test Suitability

  if number==euler_phi(total1)+euler_phi(total2):

    L.append(number)

print(L)

OUTPUT

[4, 260, 294, 740, 1460, 3140, 3860, 5540, 8420, 10820, 15140, 19940, 21860, 24020, 24260, 27620, 37460]

27620 is an abundant, Zumkeller and pseudoperfect number.

27620 can be rendered as a digit equation as follows:

-2 + 7 = 6 - 2 ^ 0