56517821 has 2 divisors, whose sum is σ = 56517822. Its totient is φ = 56517820.

The previous prime is 56517763. The next prime is 56517847. The reversal of 56517821 is 12871565.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53860921 + 2656900 = 7339^2 + 1630^2 .

It is a cyclic number.

It is not a de Polignac number, because 56517821 - 2⁶ = 56517757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (56517871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28258910 + 28258911.

It is an arithmetic number, because the mean of its divisors is an integer number (28258911).

Almost surely, 2^56517821 is an apocalyptic number.

It is an amenable number.

56517821 is a deficient number, since it is larger than the sum of its proper divisors (1).

56517821 is an equidigital number, since it uses as much as digits as its factorization.

56517821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16800, while the sum is 35.

The square root of 56517821 is about 7517.8335310114. The cubic root of 56517821 is about 383.7618536588.

The spelling of 56517821 in words is "fifty-six million, five hundred seventeen thousand, eight hundred twenty-one".