81923571 has 12 divisors (see below), whose sum is σ = 118774240. Its totient is φ = 54412560.

The previous prime is 81923551. The next prime is 81923591. The reversal of 81923571 is 17532918.

81923571 is a `hidden beast` number, since 81 + 9 + 2 + 3 + 571 = 666.

It is an interprime number because it is at equal distance from previous prime (81923551) and next prime (81923591).

It is not a de Polignac number, because 81923571 - 2⁶ = 81923507 is a prime.

It is a super-2 number, since 2×81923571² = 13422942970784082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81923551) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14356 + ... + 19233.

Almost surely, 2^81923571 is an apocalyptic number.

81923571 is a deficient number, since it is larger than the sum of its proper divisors (36850669).

81923571 is a wasteful number, since it uses less digits than its factorization.

81923571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33866 (or 33863 counting only the distinct ones).

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

The square root of 81923571 is about 9051.1640687814. The cubic root of 81923571 is about 434.3131292310.

The spelling of 81923571 in words is "eighty-one million, nine hundred twenty-three thousand, five hundred seventy-one".