81972875 has 16 divisors (see below), whose sum is σ = 103547808. Its totient is φ = 64780000.

The previous prime is 81972853. The next prime is 81972883. The reversal of 81972875 is 57827918.

81972875 = 747² + 748² + ... + 871².

It is not a de Polignac number, because 81972875 - 2⁶ = 81972811 is a prime.

It is a Duffinian number.

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, 6425 + ... + 14325.

It is an arithmetic number, because the mean of its divisors is an integer number (6471738).

Almost surely, 2^81972875 is an apocalyptic number.

81972875 is a deficient number, since it is larger than the sum of its proper divisors (21574933).

81972875 is an equidigital number, since it uses as much as digits as its factorization.

81972875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7999 (or 7989 counting only the distinct ones).

The product of its digits is 282240, while the sum is 47.

The square root of 81972875 is about 9053.8872866852. The cubic root of 81972875 is about 434.4002392042.

The spelling of 81972875 in words is "eighty-one million, nine hundred seventy-two thousand, eight hundred seventy-five".