256721902 has 4 divisors (see below), whose sum is σ = 385082856. Its totient is φ = 128360950.

The previous prime is 256721897. The next prime is 256721909. The reversal of 256721902 is 209127652.

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

It is a super-2 number, since 2×256721902² = 131812269932995208, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256721909) 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, 64180474 + ... + 64180477.

It is an arithmetic number, because the mean of its divisors is an integer number (96270714).

Almost surely, 2^256721902 is an apocalyptic number.

256721902 is a deficient number, since it is larger than the sum of its proper divisors (128360954).

256721902 is a wasteful number, since it uses less digits than its factorization.

256721902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128360953.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 256721902 is about 16022.5435558778. The cubic root of 256721902 is about 635.5567085552.

The spelling of 256721902 in words is "two hundred fifty-six million, seven hundred twenty-one thousand, nine hundred two".