20556174649 has 2 divisors, whose sum is σ = 20556174650. Its totient is φ = 20556174648.

The previous prime is 20556174647. The next prime is 20556174671. The reversal of 20556174649 is 94647165502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11557755049 + 8998419600 = 107507^2 + 94860^2 .

It is a cyclic number.

It is not a de Polignac number, because 20556174649 - 2¹ = 20556174647 is a prime.

Together with 20556174647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20556174647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10278087324 + 10278087325.

It is an arithmetic number, because the mean of its divisors is an integer number (10278087325).

Almost surely, 2^20556174649 is an apocalyptic number.

It is an amenable number.

20556174649 is a deficient number, since it is larger than the sum of its proper divisors (1).

20556174649 is an equidigital number, since it uses as much as digits as its factorization.

20556174649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1814400, while the sum is 49.

The spelling of 20556174649 in words is "twenty billion, five hundred fifty-six million, one hundred seventy-four thousand, six hundred forty-nine".