56671721 has 4 divisors (see below), whose sum is σ = 57989712. Its totient is φ = 55353732.

The previous prime is 56671709. The next prime is 56671739. The reversal of 56671721 is 12717665.

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 56671721 - 2¹⁴ = 56655337 is a prime.

It is a super-2 number, since 2×56671721² = 6423367922203682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (56671921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 658931 + ... + 659016.

It is an arithmetic number, because the mean of its divisors is an integer number (14497428).

Almost surely, 2^56671721 is an apocalyptic number.

It is an amenable number.

56671721 is a deficient number, since it is larger than the sum of its proper divisors (1317991).

56671721 is a wasteful number, since it uses less digits than its factorization.

56671721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1317990.

The product of its digits is 17640, while the sum is 35.

The square root of 56671721 is about 7528.0622340679. The cubic root of 56671721 is about 384.1098702717.

The spelling of 56671721 in words is "fifty-six million, six hundred seventy-one thousand, seven hundred twenty-one".