81890451 has 12 divisors (see below), whose sum is σ = 119907528. Its totient is φ = 53845344.

The previous prime is 81890443. The next prime is 81890483. The reversal of 81890451 is 15409818.

It is not a de Polignac number, because 81890451 - 2³ = 81890443 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81890401) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 61665 + ... + 62978.

It is an arithmetic number, because the mean of its divisors is an integer number (9992294).

Almost surely, 2^81890451 is an apocalyptic number.

81890451 is a deficient number, since it is larger than the sum of its proper divisors (38017077).

81890451 is a wasteful number, since it uses less digits than its factorization.

81890451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124722 (or 124719 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 36.

The square root of 81890451 is about 9049.3342849074. The cubic root of 81890451 is about 434.2545934130.

The spelling of 81890451 in words is "eighty-one million, eight hundred ninety thousand, four hundred fifty-one".