81977918 has 16 divisors (see below), whose sum is σ = 134285040. Its totient is φ = 37224000.

The previous prime is 81977897. The next prime is 81977921.

81977918 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×81977918² = 13440758079229448, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38588 + ... + 40656.

It is an arithmetic number, because the mean of its divisors is an integer number (8392815).

Almost surely, 2^81977918 is an apocalyptic number.

81977918 is a deficient number, since it is larger than the sum of its proper divisors (52307122).

81977918 is a wasteful number, since it uses less digits than its factorization.

81977918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3883.

The product of its digits is 254016, while the sum is 50.

The square root of 81977918 is about 9054.1657815615. The cubic root of 81977918 is about 434.4091471732.

The spelling of 81977918 in words is "eighty-one million, nine hundred seventy-seven thousand, nine hundred eighteen".