55630921 has 4 divisors (see below), whose sum is σ = 55686852. Its totient is φ = 55574992.

The previous prime is 55630871. The next prime is 55630933. The reversal of 55630921 is 12903655.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6125625 + 49505296 = 2475^2 + 7036^2 .

It is a cyclic number.

It is not a de Polignac number, because 55630921 - 2⁷ = 55630793 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55630021) 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, 26446 + ... + 28471.

It is an arithmetic number, because the mean of its divisors is an integer number (13921713).

Almost surely, 2^55630921 is an apocalyptic number.

It is an amenable number.

55630921 is a deficient number, since it is larger than the sum of its proper divisors (55931).

55630921 is a wasteful number, since it uses less digits than its factorization.

55630921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55930.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 55630921 is about 7458.6138792674. The cubic root of 55630921 is about 381.7438800155.

The spelling of 55630921 in words is "fifty-five million, six hundred thirty thousand, nine hundred twenty-one".