81923518 has 8 divisors (see below), whose sum is σ = 123186960. Its totient is φ = 40861200.

The previous prime is 81923507. The next prime is 81923537. The reversal of 81923518 is 81532918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×81923518² = 13422925602992648, 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 3 ways as a sum of consecutive naturals, for example, 49258 + ... + 50893.

It is an arithmetic number, because the mean of its divisors is an integer number (15398370).

Almost surely, 2^81923518 is an apocalyptic number.

81923518 is a deficient number, since it is larger than the sum of its proper divisors (41263442).

81923518 is a wasteful number, since it uses less digits than its factorization.

81923518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100562.

The product of its digits is 17280, while the sum is 37.

The square root of 81923518 is about 9051.1611409808. The cubic root of 81923518 is about 434.3130355722.

The spelling of 81923518 in words is "eighty-one million, nine hundred twenty-three thousand, five hundred eighteen".