815663 has 2 divisors, whose sum is σ = 815664. Its totient is φ = 815662.

The previous prime is 815653. The next prime is 815669. The reversal of 815663 is 366518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 815663 - 2⁶ = 815599 is a prime.

It is a super-2 number, since 2×815663² = 1330612259138, which contains 22 as substring.

It is equal to p₆₅₀₉₉ and since 815663 and 65099 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 815663.

It is not a weakly prime, because it can be changed into another prime (815669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 407831 + 407832.

It is an arithmetic number, because the mean of its divisors is an integer number (407832).

2⁸¹⁵⁶⁶³ is an apocalyptic number.

815663 is a deficient number, since it is larger than the sum of its proper divisors (1).

815663 is an equidigital number, since it uses as much as digits as its factorization.

815663 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 29.

The square root of 815663 is about 903.1406313526. The cubic root of 815663 is about 93.4337086227.

The spelling of 815663 in words is "eight hundred fifteen thousand, six hundred sixty-three".