55681818 has 64 divisors (see below), whose sum is σ = 123594240. Its totient is φ = 16656192.

The previous prime is 55681789. The next prime is 55681819. The reversal of 55681818 is 81818655.

It is a happy number.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 55681818.

It is not an unprimeable number, because it can be changed into a prime (55681819) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 181221 + ... + 181527.

It is an arithmetic number, because the mean of its divisors is an integer number (1931160).

Almost surely, 2^55681818 is an apocalyptic number.

55681818 is an abundant number, since it is smaller than the sum of its proper divisors (67912422).

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

55681818 is a wasteful number, since it uses less digits than its factorization.

55681818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411.

The product of its digits is 76800, while the sum is 42.

The square root of 55681818 is about 7462.0250602635. The cubic root of 55681818 is about 381.8602643062.

The spelling of 55681818 in words is "fifty-five million, six hundred eighty-one thousand, eight hundred eighteen".