55663991 has 4 divisors (see below), whose sum is σ = 55816032. Its totient is φ = 55511952.

The previous prime is 55663987. The next prime is 55663999. The reversal of 55663991 is 19936655.

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

It is a cyclic number.

It is not a de Polignac number, because 55663991 - 2² = 55663987 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 (55663999) 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, 75470 + ... + 76203.

It is an arithmetic number, because the mean of its divisors is an integer number (13954008).

Almost surely, 2^55663991 is an apocalyptic number.

55663991 is a deficient number, since it is larger than the sum of its proper divisors (152041).

55663991 is a wasteful number, since it uses less digits than its factorization.

55663991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152040.

The product of its digits is 218700, while the sum is 44.

The square root of 55663991 is about 7460.8304497556. The cubic root of 55663991 is about 381.8195080367.

The spelling of 55663991 in words is "fifty-five million, six hundred sixty-three thousand, nine hundred ninety-one".