81421968 has 20 divisors (see below), whose sum is σ = 210340208. Its totient is φ = 27140640.

The previous prime is 81421961. The next prime is 81421981. The reversal of 81421968 is 86912418.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81421961) 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, 848098 + ... + 848193.

Almost surely, 2^81421968 is an apocalyptic number.

It is an amenable number.

81421968 is an abundant number, since it is smaller than the sum of its proper divisors (128918240).

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

81421968 is a wasteful number, since it uses less digits than its factorization.

81421968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696302 (or 1696296 counting only the distinct ones).

The product of its digits is 27648, while the sum is 39.

The square root of 81421968 is about 9023.4122148996. The cubic root of 81421968 is about 433.4249074055.

The spelling of 81421968 in words is "eighty-one million, four hundred twenty-one thousand, nine hundred sixty-eight".