81920818 has 32 divisors (see below), whose sum is σ = 148515840. Its totient is φ = 33106320.

The previous prime is 81920791. The next prime is 81920843. The reversal of 81920818 is 81802918.

It is a super-2 number, since 2×81920818² = 13422040843578248, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69373 + ... + 70543.

It is an arithmetic number, because the mean of its divisors is an integer number (4641120).

Almost surely, 2^81920818 is an apocalyptic number.

81920818 is a deficient number, since it is larger than the sum of its proper divisors (66595022).

81920818 is a wasteful number, since it uses less digits than its factorization.

81920818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1462.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 81920818 is about 9051.0119876177. The cubic root of 81920818 is about 434.3082642191.

The spelling of 81920818 in words is "eighty-one million, nine hundred twenty thousand, eight hundred eighteen".