81974165 has 32 divisors (see below), whose sum is σ = 122922240. Its totient is φ = 51093504.

The previous prime is 81974149. The next prime is 81974171. The reversal of 81974165 is 56147918.

It is not a de Polignac number, because 81974165 - 2⁴ = 81974149 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 29141 + ... + 31829.

It is an arithmetic number, because the mean of its divisors is an integer number (3841320).

Almost surely, 2^81974165 is an apocalyptic number.

It is an amenable number.

81974165 is a deficient number, since it is larger than the sum of its proper divisors (40948075).

81974165 is a wasteful number, since it uses less digits than its factorization.

81974165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2781.

The product of its digits is 60480, while the sum is 41.

The square root of 81974165 is about 9053.9585265231. The cubic root of 81974165 is about 434.4025178985.

The spelling of 81974165 in words is "eighty-one million, nine hundred seventy-four thousand, one hundred sixty-five".