256642399 has 4 divisors (see below), whose sum is σ = 276384136. Its totient is φ = 236900664.

The previous prime is 256642363. The next prime is 256642417. The reversal of 256642399 is 993246652.

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

It is not a de Polignac number, because 256642399 - 2¹⁷ = 256511327 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 (256642499) 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, 9870849 + ... + 9870874.

It is an arithmetic number, because the mean of its divisors is an integer number (69096034).

Almost surely, 2^256642399 is an apocalyptic number.

256642399 is a deficient number, since it is larger than the sum of its proper divisors (19741737).

256642399 is a wasteful number, since it uses less digits than its factorization.

256642399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19741736.

The product of its digits is 699840, while the sum is 46.

The square root of 256642399 is about 16020.0623906401. The cubic root of 256642399 is about 635.4910942575.

The spelling of 256642399 in words is "two hundred fifty-six million, six hundred forty-two thousand, three hundred ninety-nine".