656242621 has 2 divisors, whose sum is σ = 656242622. Its totient is φ = 656242620.

The previous prime is 656242607. The next prime is 656242649. The reversal of 656242621 is 126242656.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 643383225 + 12859396 = 25365^2 + 3586^2 .

It is a cyclic number.

It is not a de Polignac number, because 656242621 - 2¹¹ = 656240573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (656242681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328121310 + 328121311.

It is an arithmetic number, because the mean of its divisors is an integer number (328121311).

Almost surely, 2^656242621 is an apocalyptic number.

It is an amenable number.

656242621 is a deficient number, since it is larger than the sum of its proper divisors (1).

656242621 is an equidigital number, since it uses as much as digits as its factorization.

656242621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 34.

The square root of 656242621 is about 25617.2328911614. The cubic root of 656242621 is about 869.0034041173.

The spelling of 656242621 in words is "six hundred fifty-six million, two hundred forty-two thousand, six hundred twenty-one".