81559793 has 4 divisors (see below), whose sum is σ = 93211200. Its totient is φ = 69908388.

The previous prime is 81559789. The next prime is 81559811. The reversal of 81559793 is 39795518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81559793 - 2² = 81559789 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81559493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5825693 + ... + 5825706.

It is an arithmetic number, because the mean of its divisors is an integer number (23302800).

Almost surely, 2^81559793 is an apocalyptic number.

It is an amenable number.

81559793 is a deficient number, since it is larger than the sum of its proper divisors (11651407).

81559793 is a wasteful number, since it uses less digits than its factorization.

81559793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11651406.

The product of its digits is 340200, while the sum is 47.

The square root of 81559793 is about 9031.0460634414. The cubic root of 81559793 is about 433.6693259369.

The spelling of 81559793 in words is "eighty-one million, five hundred fifty-nine thousand, seven hundred ninety-three".