81911658 has 8 divisors (see below), whose sum is σ = 163823328. Its totient is φ = 27303884.

The previous prime is 81911633. The next prime is 81911681. The reversal of 81911658 is 85611918.

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

81911658 is an admirable 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, 6825966 + ... + 6825977.

It is an arithmetic number, because the mean of its divisors is an integer number (20477916).

Almost surely, 2^81911658 is an apocalyptic number.

81911658 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81911658 is a wasteful number, since it uses less digits than its factorization.

81911658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13651948.

The product of its digits is 17280, while the sum is 39.

The square root of 81911658 is about 9050.5059527078. The cubic root of 81911658 is about 434.2920761810.

The spelling of 81911658 in words is "eighty-one million, nine hundred eleven thousand, six hundred fifty-eight".