81937971 has 6 divisors (see below), whose sum is σ = 118354860. Its totient is φ = 54625308.

The previous prime is 81937951. The next prime is 81937979. The reversal of 81937971 is 17973918.

It is not a de Polignac number, because 81937971 - 2⁹ = 81937459 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81937979) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4552101 + ... + 4552118.

It is an arithmetic number, because the mean of its divisors is an integer number (19725810).

Almost surely, 2^81937971 is an apocalyptic number.

81937971 is a deficient number, since it is larger than the sum of its proper divisors (36416889).

81937971 is a wasteful number, since it uses less digits than its factorization.

81937971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9104225 (or 9104222 counting only the distinct ones).

The product of its digits is 95256, while the sum is 45.

The square root of 81937971 is about 9051.9595116196. The cubic root of 81937971 is about 434.3385746658.

The spelling of 81937971 in words is "eighty-one million, nine hundred thirty-seven thousand, nine hundred seventy-one".