81891948 has 12 divisors (see below), whose sum is σ = 191081240. Its totient is φ = 27297312.

The previous prime is 81891893. The next prime is 81891949. The reversal of 81891948 is 84919818.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×81891948² = 13412582294469408, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81891897 and 81891906.

It is not an unprimeable number, because it can be changed into a prime (81891949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3412153 + ... + 3412176.

Almost surely, 2^81891948 is an apocalyptic number.

It is an amenable number.

81891948 is an abundant number, since it is smaller than the sum of its proper divisors (109189292).

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

81891948 is a wasteful number, since it uses less digits than its factorization.

81891948 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6824336 (or 6824334 counting only the distinct ones).

The product of its digits is 165888, while the sum is 48.

The square root of 81891948 is about 9049.4169977960. The cubic root of 81891948 is about 434.2572395301.

The spelling of 81891948 in words is "eighty-one million, eight hundred ninety-one thousand, nine hundred forty-eight".