81911420 has 24 divisors (see below), whose sum is σ = 172186224. Its totient is φ = 32731776.

The previous prime is 81911407. The next prime is 81911437. The reversal of 81911420 is 2411918.

It is a self number, because there is not a number n which added to its sum of digits gives 81911420.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33272 + ... + 35648.

It is an arithmetic number, because the mean of its divisors is an integer number (7174426).

Almost surely, 2^81911420 is an apocalyptic number.

It is an amenable number.

81911420 is an abundant number, since it is smaller than the sum of its proper divisors (90274804).

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

81911420 is a wasteful number, since it uses less digits than its factorization.

81911420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4109 (or 4107 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 81911420 is about 9050.4928042621. The cubic root of 81911420 is about 434.2916555586.

The spelling of 81911420 in words is "eighty-one million, nine hundred eleven thousand, four hundred twenty".