56691521 has 2 divisors, whose sum is σ = 56691522. Its totient is φ = 56691520.

The previous prime is 56691493. The next prime is 56691533. The reversal of 56691521 is 12519665.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53217025 + 3474496 = 7295^2 + 1864^2 .

It is a cyclic number.

It is not a de Polignac number, because 56691521 - 2⁶ = 56691457 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (56691121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28345760 + 28345761.

It is an arithmetic number, because the mean of its divisors is an integer number (28345761).

Almost surely, 2^56691521 is an apocalyptic number.

It is an amenable number.

56691521 is a deficient number, since it is larger than the sum of its proper divisors (1).

56691521 is an equidigital number, since it uses as much as digits as its factorization.

56691521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 35.

The square root of 56691521 is about 7529.3771986798. The cubic root of 56691521 is about 384.1545985756.

The spelling of 56691521 in words is "fifty-six million, six hundred ninety-one thousand, five hundred twenty-one".