56721621 has 16 divisors (see below), whose sum is σ = 84261888. Its totient is φ = 33644400.

The previous prime is 56721589. The next prime is 56721647. The reversal of 56721621 is 12612765.

It is not a de Polignac number, because 56721621 - 2⁵ = 56721589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56721671) 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 in 15 ways as a sum of consecutive naturals, for example, 16735 + ... + 19836.

It is an arithmetic number, because the mean of its divisors is an integer number (5266368).

Almost surely, 2^56721621 is an apocalyptic number.

It is an amenable number.

56721621 is a deficient number, since it is larger than the sum of its proper divisors (27540267).

56721621 is a wasteful number, since it uses less digits than its factorization.

56721621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36632.

The product of its digits is 5040, while the sum is 30.

The square root of 56721621 is about 7531.3757707341. The cubic root of 56721621 is about 384.2225746878. Note that the first 3 decimals are identical.

The spelling of 56721621 in words is "fifty-six million, seven hundred twenty-one thousand, six hundred twenty-one".