81972351 has 32 divisors (see below), whose sum is σ = 129254400. Its totient is φ = 51166080.

The previous prime is 81972329. The next prime is 81972361. The reversal of 81972351 is 15327918.

It is not a de Polignac number, because 81972351 - 2⁶ = 81972287 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81972301) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 124060 + ... + 124718.

It is an arithmetic number, because the mean of its divisors is an integer number (4039200).

Almost surely, 2^81972351 is an apocalyptic number.

81972351 is a deficient number, since it is larger than the sum of its proper divisors (47282049).

81972351 is a wasteful number, since it uses less digits than its factorization.

81972351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 956 (or 950 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 81972351 is about 9053.8583487925. The cubic root of 81972351 is about 434.3993135882.

The spelling of 81972351 in words is "eighty-one million, nine hundred seventy-two thousand, three hundred fifty-one".