256990389 has 4 divisors (see below), whose sum is σ = 342653856. Its totient is φ = 171326924.

The previous prime is 256990381. The next prime is 256990399. The reversal of 256990389 is 983099652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 256990389 - 2³ = 256990381 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256990381) 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, 42831729 + ... + 42831734.

It is an arithmetic number, because the mean of its divisors is an integer number (85663464).

Almost surely, 2^256990389 is an apocalyptic number.

It is an amenable number.

256990389 is a deficient number, since it is larger than the sum of its proper divisors (85663467).

256990389 is an equidigital number, since it uses as much as digits as its factorization.

256990389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85663466.

The product of its (nonzero) digits is 1049760, while the sum is 51.

The square root of 256990389 is about 16030.9197802247. The cubic root of 256990389 is about 635.7781924007.

The spelling of 256990389 in words is "two hundred fifty-six million, nine hundred ninety thousand, three hundred eighty-nine".