81890784 has 48 divisors (see below), whose sum is σ = 238850640. Its totient is φ = 27296640.

The previous prime is 81890759. The next prime is 81890789. The reversal of 81890784 is 48709818.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×81890784² = 13412201008269312, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81890789) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46527 + ... + 48254.

It is an arithmetic number, because the mean of its divisors is an integer number (4976055).

Almost surely, 2^81890784 is an apocalyptic number.

It is an amenable number.

81890784 is an abundant number, since it is smaller than the sum of its proper divisors (156959856).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81890784 is a wasteful number, since it uses less digits than its factorization.

81890784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94800 (or 94786 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 81890784 is about 9049.3526840322. The cubic root of 81890784 is about 434.2551820310.

The spelling of 81890784 in words is "eighty-one million, eight hundred ninety thousand, seven hundred eighty-four".