81571384 has 16 divisors (see below), whose sum is σ = 157080600. Its totient is φ = 39683232.

The previous prime is 81571331. The next prime is 81571433. The reversal of 81571384 is 48317518.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 137494 + ... + 138085.

Almost surely, 2^81571384 is an apocalyptic number.

It is an amenable number.

81571384 is a deficient number, since it is larger than the sum of its proper divisors (75509216).

81571384 is a wasteful number, since it uses less digits than its factorization.

81571384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275622 (or 275618 counting only the distinct ones).

The product of its digits is 26880, while the sum is 37.

The square root of 81571384 is about 9031.6877713969. The cubic root of 81571384 is about 433.6898688330.

The spelling of 81571384 in words is "eighty-one million, five hundred seventy-one thousand, three hundred eighty-four".