56665621 has 2 divisors, whose sum is σ = 56665622. Its totient is φ = 56665620.

The previous prime is 56665603. The next prime is 56665627. The reversal of 56665621 is 12656665.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45037521 + 11628100 = 6711^2 + 3410^2 .

It is a cyclic number.

It is not a de Polignac number, because 56665621 - 2¹⁷ = 56534549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (56665627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28332810 + 28332811.

It is an arithmetic number, because the mean of its divisors is an integer number (28332811).

Almost surely, 2^56665621 is an apocalyptic number.

It is an amenable number.

56665621 is a deficient number, since it is larger than the sum of its proper divisors (1).

56665621 is an equidigital number, since it uses as much as digits as its factorization.

56665621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64800, while the sum is 37.

The square root of 56665621 is about 7527.6570724230. The cubic root of 56665621 is about 384.0960882405.

The spelling of 56665621 in words is "fifty-six million, six hundred sixty-five thousand, six hundred twenty-one".