56621821 has 2 divisors, whose sum is σ = 56621822. Its totient is φ = 56621820.

The previous prime is 56621819. The next prime is 56621827. The reversal of 56621821 is 12812665.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49196196 + 7425625 = 7014^2 + 2725^2 .

It is a cyclic number.

It is not a de Polignac number, because 56621821 - 2¹ = 56621819 is a prime.

It is a super-2 number, since 2×56621821² = 6412061226712082, which contains 22 as substring.

Together with 56621819, 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 (56621827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28310910 + 28310911.

It is an arithmetic number, because the mean of its divisors is an integer number (28310911).

Almost surely, 2^56621821 is an apocalyptic number.

It is an amenable number.

56621821 is a deficient number, since it is larger than the sum of its proper divisors (1).

56621821 is an equidigital number, since it uses as much as digits as its factorization.

56621821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 31.

The square root of 56621821 is about 7524.7472382798. The cubic root of 56621821 is about 383.9970996779.

The spelling of 56621821 in words is "fifty-six million, six hundred twenty-one thousand, eight hundred twenty-one".