81994690 has 32 divisors (see below), whose sum is σ = 160381440. Its totient is φ = 30067200.

The previous prime is 81994681. The next prime is 81994691. The reversal of 81994690 is 9649918.

It is a super-2 number, since 2×81994690² = 13446258376392200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81994690.

It is not an unprimeable number, because it can be changed into a prime (81994691) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1071 + ... + 12850.

It is an arithmetic number, because the mean of its divisors is an integer number (5011920).

Almost surely, 2^81994690 is an apocalyptic number.

81994690 is a deficient number, since it is larger than the sum of its proper divisors (78386750).

81994690 is a wasteful number, since it uses less digits than its factorization.

81994690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13978.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 81994690 is about 9055.0919376890. The cubic root of 81994690 is about 434.4387706522.

The spelling of 81994690 in words is "eighty-one million, nine hundred ninety-four thousand, six hundred ninety".