55991665 has 16 divisors (see below), whose sum is σ = 68808960. Its totient is φ = 43727040.

The previous prime is 55991603. The next prime is 55991669. The reversal of 55991665 is 56619955.

It is a happy number.

It is not a de Polignac number, because 55991665 - 2¹⁵ = 55958897 is a prime.

It is not an unprimeable number, because it can be changed into a prime (55991669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 37972 + ... + 39418.

It is an arithmetic number, because the mean of its divisors is an integer number (4300560).

Almost surely, 2^55991665 is an apocalyptic number.

It is an amenable number.

55991665 is a deficient number, since it is larger than the sum of its proper divisors (12817295).

55991665 is a wasteful number, since it uses less digits than its factorization.

55991665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1632.

The product of its digits is 364500, while the sum is 46.

The square root of 55991665 is about 7482.7578472111. The cubic root of 55991665 is about 382.5672543253.

The spelling of 55991665 in words is "fifty-five million, nine hundred ninety-one thousand, six hundred sixty-five".