656264646421 has 2 divisors, whose sum is σ = 656264646422. Its totient is φ = 656264646420.

The previous prime is 656264646419. The next prime is 656264646449. The reversal of 656264646421 is 124646462656.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 576709623396 + 79555023025 = 759414^2 + 282055^2 .

It is a cyclic number.

It is not a de Polignac number, because 656264646421 - 2¹ = 656264646419 is a prime.

It is a super-2 number, since 2×656264646421² (a number of 24 digits) contains 22 as substring.

Together with 656264646419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656264646481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328132323210 + 328132323211.

It is an arithmetic number, because the mean of its divisors is an integer number (328132323211).

Almost surely, 2^656264646421 is an apocalyptic number.

It is an amenable number.

656264646421 is a deficient number, since it is larger than the sum of its proper divisors (1).

656264646421 is an equidigital number, since it uses as much as digits as its factorization.

656264646421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9953280, while the sum is 52.

The spelling of 656264646421 in words is "six hundred fifty-six billion, two hundred sixty-four million, six hundred forty-six thousand, four hundred twenty-one".