56721637 has 4 divisors (see below), whose sum is σ = 64824736. Its totient is φ = 48618540.

The previous prime is 56721589. The next prime is 56721647. The reversal of 56721637 is 73612765.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 56721637 - 2¹⁵ = 56688869 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 56721596 and 56721605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56721647) 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 3 ways as a sum of consecutive naturals, for example, 4051539 + ... + 4051552.

It is an arithmetic number, because the mean of its divisors is an integer number (16206184).

Almost surely, 2^56721637 is an apocalyptic number.

It is an amenable number.

56721637 is a deficient number, since it is larger than the sum of its proper divisors (8103099).

56721637 is an equidigital number, since it uses as much as digits as its factorization.

56721637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8103098.

The product of its digits is 52920, while the sum is 37.

The square root of 56721637 is about 7531.3768329569. The cubic root of 56721637 is about 384.2226108149. Note that the first 3 decimals are identical.

The spelling of 56721637 in words is "fifty-six million, seven hundred twenty-one thousand, six hundred thirty-seven".