256399807 has 2 divisors, whose sum is σ = 256399808. Its totient is φ = 256399806.

The previous prime is 256399799. The next prime is 256399823. The reversal of 256399807 is 708993652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256399807 - 2³ = 256399799 is a prime.

It is a super-2 number, since 2×256399807² = 131481722059274498, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256399867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128199903 + 128199904.

It is an arithmetic number, because the mean of its divisors is an integer number (128199904).

Almost surely, 2^256399807 is an apocalyptic number.

256399807 is a deficient number, since it is larger than the sum of its proper divisors (1).

256399807 is an equidigital number, since it uses as much as digits as its factorization.

256399807 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 816480, while the sum is 49.

The square root of 256399807 is about 16012.4890944537. The cubic root of 256399807 is about 635.2907978442.

The spelling of 256399807 in words is "two hundred fifty-six million, three hundred ninety-nine thousand, eight hundred seven".