55771815 has 64 divisors (see below), whose sum is σ = 105131520. Its totient is φ = 24944640.

The previous prime is 55771813. The next prime is 55771819. The reversal of 55771815 is 51817755.

It is a happy number.

It is not a de Polignac number, because 55771815 - 2¹ = 55771813 is a prime.

It is a super-2 number, since 2×55771815² = 6220990696788450, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55771811) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 165327 + ... + 165663.

It is an arithmetic number, because the mean of its divisors is an integer number (1642680).

Almost surely, 2^55771815 is an apocalyptic number.

55771815 is a gapful number since it is divisible by the number (55) formed by its first and last digit.

55771815 is a deficient number, since it is larger than the sum of its proper divisors (49359705).

55771815 is a wasteful number, since it uses less digits than its factorization.

55771815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432.

The product of its digits is 49000, while the sum is 39.

The square root of 55771815 is about 7468.0529591052. The cubic root of 55771815 is about 382.0658836685.

The spelling of 55771815 in words is "fifty-five million, seven hundred seventy-one thousand, eight hundred fifteen".