257221691 has 4 divisors (see below), whose sum is σ = 257262000. Its totient is φ = 257181384.

The previous prime is 257221681. The next prime is 257221693. The reversal of 257221691 is 196122752.

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

It is a cyclic number.

It is not a de Polignac number, because 257221691 - 2²² = 253027387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257221693) 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, 8231 + ... + 24128.

It is an arithmetic number, because the mean of its divisors is an integer number (64315500).

Almost surely, 2^257221691 is an apocalyptic number.

257221691 is a deficient number, since it is larger than the sum of its proper divisors (40309).

257221691 is an equidigital number, since it uses as much as digits as its factorization.

257221691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40308.

The product of its digits is 15120, while the sum is 35.

The square root of 257221691 is about 16038.1324037433. The cubic root of 257221691 is about 635.9688774441.

The spelling of 257221691 in words is "two hundred fifty-seven million, two hundred twenty-one thousand, six hundred ninety-one".