81733665 has 16 divisors (see below), whose sum is σ = 140833728. Its totient is φ = 40238016.

The previous prime is 81733657. The next prime is 81733667. The reversal of 81733665 is 56633718.

It is not a de Polignac number, because 81733665 - 2³ = 81733657 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (81733667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 209379 + ... + 209768.

It is an arithmetic number, because the mean of its divisors is an integer number (8802108).

Almost surely, 2^81733665 is an apocalyptic number.

It is an amenable number.

81733665 is a deficient number, since it is larger than the sum of its proper divisors (59100063).

81733665 is a wasteful number, since it uses less digits than its factorization.

81733665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 419168.

The product of its digits is 90720, while the sum is 39.

The square root of 81733665 is about 9040.6672873190. The cubic root of 81733665 is about 433.9772776512.

The spelling of 81733665 in words is "eighty-one million, seven hundred thirty-three thousand, six hundred sixty-five".