257720991 has 8 divisors (see below), whose sum is σ = 374866944. Its totient is φ = 156194520.

The previous prime is 257720987. The next prime is 257721001. The reversal of 257720991 is 199027752.

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

It is not a de Polignac number, because 257720991 - 2² = 257720987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257720971) 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, 3904831 + ... + 3904896.

It is an arithmetic number, because the mean of its divisors is an integer number (46858368).

Almost surely, 2^257720991 is an apocalyptic number.

257720991 is a deficient number, since it is larger than the sum of its proper divisors (117145953).

257720991 is a wasteful number, since it uses less digits than its factorization.

257720991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7809741.

The product of its (nonzero) digits is 79380, while the sum is 42.

The square root of 257720991 is about 16053.6908840304. The cubic root of 257720991 is about 636.3801102853.

The spelling of 257720991 in words is "two hundred fifty-seven million, seven hundred twenty thousand, nine hundred ninety-one".