55991997 has 12 divisors (see below), whose sum is σ = 81227484. Its totient is φ = 37166400.

The previous prime is 55991987. The next prime is 55992017. The reversal of 55991997 is 79919955.

It can be written as a sum of positive squares in 2 ways, for example, as 7257636 + 48734361 = 2694^2 + 6981^2 .

It is not a de Polignac number, because 55991997 - 2⁴ = 55991981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55991987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11254 + ... + 15447.

It is an arithmetic number, because the mean of its divisors is an integer number (6768957).

Almost surely, 2^55991997 is an apocalyptic number.

It is an amenable number.

55991997 is a deficient number, since it is larger than the sum of its proper divisors (25235487).

55991997 is a wasteful number, since it uses less digits than its factorization.

55991997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26940 (or 26937 counting only the distinct ones).

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

The square root of 55991997 is about 7482.7800315124. The cubic root of 55991997 is about 382.5680104621.

The spelling of 55991997 in words is "fifty-five million, nine hundred ninety-one thousand, nine hundred ninety-seven".