815851 has 2 divisors, whose sum is σ = 815852. Its totient is φ = 815850.

The previous prime is 815831. The next prime is 815869. The reversal of 815851 is 158518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 815851 - 2⁵ = 815819 is a prime.

It is a super-2 number, since 2×815851² = 1331225708402, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (815821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407925 + 407926.

It is an arithmetic number, because the mean of its divisors is an integer number (407926).

2⁸¹⁵⁸⁵¹ is an apocalyptic number.

815851 is a deficient number, since it is larger than the sum of its proper divisors (1).

815851 is an equidigital number, since it uses as much as digits as its factorization.

815851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1600, while the sum is 28.

The square root of 815851 is about 903.2447065995. The cubic root of 815851 is about 93.4408865005.

The spelling of 815851 in words is "eight hundred fifteen thousand, eight hundred fifty-one".