256204991 has 16 divisors (see below), whose sum is σ = 298579968. Its totient is φ = 215308800.

The previous prime is 256204951. The next prime is 256204997. The reversal of 256204991 is 199402652.

It is not a de Polignac number, because 256204991 - 2¹⁸ = 255942847 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 (256204997) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 94586 + ... + 97256.

It is an arithmetic number, because the mean of its divisors is an integer number (18661248).

Almost surely, 2^256204991 is an apocalyptic number.

256204991 is a deficient number, since it is larger than the sum of its proper divisors (42374977).

256204991 is a wasteful number, since it uses less digits than its factorization.

256204991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2942.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 256204991 is about 16006.4046868746. The cubic root of 256204991 is about 635.1298562626.

The spelling of 256204991 in words is "two hundred fifty-six million, two hundred four thousand, nine hundred ninety-one".