55991664 has 60 divisors (see below), whose sum is σ = 160052256. Its totient is φ = 18264576.

The previous prime is 55991603. The next prime is 55991669. The reversal of 55991664 is 46619955.

It is a happy number.

55991664 is a `hidden beast` number, since 559 + 91 + 6 + 6 + 4 = 666.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

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 11 ways as a sum of consecutive naturals, for example, 2632 + ... + 10904.

Almost surely, 2^55991664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 55991664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80026128).

55991664 is an abundant number, since it is smaller than the sum of its proper divisors (104060592).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

55991664 is a wasteful number, since it uses less digits than its factorization.

55991664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8334 (or 8325 counting only the distinct ones).

The product of its digits is 291600, while the sum is 45.

The square root of 55991664 is about 7482.7577803909. The cubic root of 55991664 is about 382.5672520478.

The spelling of 55991664 in words is "fifty-five million, nine hundred ninety-one thousand, six hundred sixty-four".