55997991 has 12 divisors (see below), whose sum is σ = 92441232. Its totient is φ = 31998816.

The previous prime is 55997989. The next prime is 55998001. The reversal of 55997991 is 19979955.

It is not a de Polignac number, because 55997991 - 2¹ = 55997989 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55993991) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 444366 + ... + 444491.

It is an arithmetic number, because the mean of its divisors is an integer number (7703436).

Almost surely, 2^55997991 is an apocalyptic number.

55997991 is a deficient number, since it is larger than the sum of its proper divisors (36443241).

55997991 is a wasteful number, since it uses less digits than its factorization.

55997991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 888870 (or 888867 counting only the distinct ones).

The product of its digits is 1148175, while the sum is 54.

The square root of 55997991 is about 7483.1805403852. The cubic root of 55997991 is about 382.5816614060.

The spelling of 55997991 in words is "fifty-five million, nine hundred ninety-seven thousand, nine hundred ninety-one".