81939340 has 48 divisors (see below), whose sum is σ = 205212672. Its totient is φ = 26870976.

The previous prime is 81939313. The next prime is 81939359. The reversal of 81939340 is 4393918.

It is a self number, because there is not a number n which added to its sum of digits gives 81939340.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9504 + ... + 15943.

It is an arithmetic number, because the mean of its divisors is an integer number (4275264).

Almost surely, 2^81939340 is an apocalyptic number.

It is an amenable number.

81939340 is an abundant number, since it is smaller than the sum of its proper divisors (123273332).

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

81939340 is a wasteful number, since it uses less digits than its factorization.

81939340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25486 (or 25484 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 81939340 is about 9052.0351302898. The cubic root of 81939340 is about 434.3409935940.

The spelling of 81939340 in words is "eighty-one million, nine hundred thirty-nine thousand, three hundred forty".