81939377 has 16 divisors (see below), whose sum is σ = 91687680. Its totient is φ = 72740352.

The previous prime is 81939373. The next prime is 81939391. The reversal of 81939377 is 77393918.

It is a cyclic number.

It is not a de Polignac number, because 81939377 - 2² = 81939373 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81939373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34913 + ... + 37185.

It is an arithmetic number, because the mean of its divisors is an integer number (5730480).

Almost surely, 2^81939377 is an apocalyptic number.

It is an amenable number.

81939377 is a deficient number, since it is larger than the sum of its proper divisors (9748303).

81939377 is a wasteful number, since it uses less digits than its factorization.

81939377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2392.

The product of its digits is 285768, while the sum is 47.

The square root of 81939377 is about 9052.0371740288. The cubic root of 81939377 is about 434.3410589701.

The spelling of 81939377 in words is "eighty-one million, nine hundred thirty-nine thousand, three hundred seventy-seven".