518981661 has 88 divisors (see below), whose sum is σ = 918324864. Its totient is φ = 289733760.

The previous prime is 518981629. The next prime is 518981699. The reversal of 518981661 is 166189815.

It is not a de Polignac number, because 518981661 - 2⁵ = 518981629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (518981621) by changing a digit.

It is a polite number, since it can be written in 87 ways as a sum of consecutive naturals, for example, 11042140 + ... + 11042186.

Almost surely, 2^518981661 is an apocalyptic number.

518981661 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

518981661 is a deficient number, since it is larger than the sum of its proper divisors (399343203).

518981661 is an equidigital number, since it uses as much as digits as its factorization.

518981661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105 (or 78 counting only the distinct ones).

The product of its digits is 103680, while the sum is 45.

The square root of 518981661 is about 22781.1689998560. The cubic root of 518981661 is about 803.6198776731.

The spelling of 518981661 in words is "five hundred eighteen million, nine hundred eighty-one thousand, six hundred sixty-one".