256631551 has 8 divisors (see below), whose sum is σ = 282006864. Its totient is φ = 231597120.

The previous prime is 256631513. The next prime is 256631563. The reversal of 256631551 is 155136652.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 256631551 - 2¹⁹ = 256107263 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 (256631581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 83640 + ... + 86653.

It is an arithmetic number, because the mean of its divisors is an integer number (35250858).

Almost surely, 2^256631551 is an apocalyptic number.

256631551 is a deficient number, since it is larger than the sum of its proper divisors (25375313).

256631551 is a wasteful number, since it uses less digits than its factorization.

256631551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170441.

The product of its digits is 27000, while the sum is 34.

The square root of 256631551 is about 16019.7238116017. The cubic root of 256631551 is about 635.4821402881.

The spelling of 256631551 in words is "two hundred fifty-six million, six hundred thirty-one thousand, five hundred fifty-one".