81657793 has 8 divisors (see below), whose sum is σ = 94248000. Its totient is φ = 69298800.

The previous prime is 81657787. The next prime is 81657827. The reversal of 81657793 is 39775618.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81657793 - 2²¹ = 79560641 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81657733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57043 + ... + 58456.

It is an arithmetic number, because the mean of its divisors is an integer number (11781000).

Almost surely, 2^81657793 is an apocalyptic number.

It is an amenable number.

81657793 is a deficient number, since it is larger than the sum of its proper divisors (12590207).

81657793 is a wasteful number, since it uses less digits than its factorization.

81657793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115607.

The product of its digits is 317520, while the sum is 46.

The square root of 81657793 is about 9036.4701626243. The cubic root of 81657793 is about 433.8429514519.

The spelling of 81657793 in words is "eighty-one million, six hundred fifty-seven thousand, seven hundred ninety-three".