81571516 has 36 divisors (see below), whose sum is σ = 158133976. Its totient is φ = 36580320.

The previous prime is 81571507. The next prime is 81571517. The reversal of 81571516 is 61517518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81571517) 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, 426981 + ... + 427171.

Almost surely, 2^81571516 is an apocalyptic number.

81571516 is a gapful number since it is divisible by the number (86) formed by its first and last digit.

It is an amenable number.

81571516 is a deficient number, since it is larger than the sum of its proper divisors (76562460).

81571516 is a wasteful number, since it uses less digits than its factorization.

81571516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442 (or 249 counting only the distinct ones).

The product of its digits is 8400, while the sum is 34.

The square root of 81571516 is about 9031.6950789982. The cubic root of 81571516 is about 433.6901027673.

The spelling of 81571516 in words is "eighty-one million, five hundred seventy-one thousand, five hundred sixteen".