81972577 has 8 divisors (see below), whose sum is σ = 84062880. Its totient is φ = 79890720.

The previous prime is 81972563. The next prime is 81972581. The reversal of 81972577 is 77527918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81972577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81978577) 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 7 ways as a sum of consecutive naturals, for example, 20574 + ... + 24232.

It is an arithmetic number, because the mean of its divisors is an integer number (10507860).

Almost surely, 2^81972577 is an apocalyptic number.

It is an amenable number.

81972577 is a deficient number, since it is larger than the sum of its proper divisors (2090303).

81972577 is a wasteful number, since it uses less digits than its factorization.

81972577 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4223.

The product of its digits is 246960, while the sum is 46.

The square root of 81972577 is about 9053.8708296507. The cubic root of 81972577 is about 434.3997128048.

The spelling of 81972577 in words is "eighty-one million, nine hundred seventy-two thousand, five hundred seventy-seven".