55978021 has 16 divisors (see below), whose sum is σ = 64407168. Its totient is φ = 48153600.

The previous prime is 55978007. The next prime is 55978049. The reversal of 55978021 is 12087955.

It is not a de Polignac number, because 55978021 - 2⁵ = 55977989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55978001) 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, 23401 + ... + 25681.

It is an arithmetic number, because the mean of its divisors is an integer number (4025448).

Almost surely, 2^55978021 is an apocalyptic number.

It is an amenable number.

55978021 is a deficient number, since it is larger than the sum of its proper divisors (8429147).

55978021 is a wasteful number, since it uses less digits than its factorization.

55978021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2412.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 55978021 is about 7481.8460957173. The cubic root of 55978021 is about 382.5361772495.

The spelling of 55978021 in words is "fifty-five million, nine hundred seventy-eight thousand, twenty-one".