81807959 has 4 divisors (see below), whose sum is σ = 81858816. Its totient is φ = 81757104.

The previous prime is 81807953. The next prime is 81807967. The reversal of 81807959 is 95970818.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81807959 - 2²⁰ = 80759383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81807953) 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, 22934 + ... + 26259.

It is an arithmetic number, because the mean of its divisors is an integer number (20464704).

Almost surely, 2^81807959 is an apocalyptic number.

81807959 is a deficient number, since it is larger than the sum of its proper divisors (50857).

81807959 is a wasteful number, since it uses less digits than its factorization.

81807959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50856.

The product of its (nonzero) digits is 181440, while the sum is 47.

The square root of 81807959 is about 9044.7752321437. The cubic root of 81807959 is about 434.1087295800.

The spelling of 81807959 in words is "eighty-one million, eight hundred seven thousand, nine hundred fifty-nine".