815881 has 8 divisors (see below), whose sum is σ = 942624. Its totient is φ = 697920.

The previous prime is 815869. The next prime is 815891. The reversal of 815881 is 188518.

It is a happy number.

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 815881 - 2¹¹ = 813833 is a prime.

It is a super-2 number, since 2×815881² = 1331323612322, which contains 22 as substring.

It is a Duffinian number.

815881 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (815821) 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, 1995 + ... + 2368.

It is an arithmetic number, because the mean of its divisors is an integer number (117828).

2⁸¹⁵⁸⁸¹ is an apocalyptic number.

It is an amenable number.

815881 is a deficient number, since it is larger than the sum of its proper divisors (126743).

815881 is a wasteful number, since it uses less digits than its factorization.

815881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4391.

The product of its digits is 2560, while the sum is 31.

The square root of 815881 is about 903.2613132422. The cubic root of 815881 is about 93.4420318045.

The spelling of 815881 in words is "eight hundred fifteen thousand, eight hundred eighty-one".