257661521 has 4 divisors (see below), whose sum is σ = 277481652. Its totient is φ = 237841392.

The previous prime is 257661511. The next prime is 257661539. The reversal of 257661521 is 125166752.

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

It can be written as a sum of positive squares in 2 ways, for example, as 24641296 + 233020225 = 4964^2 + 15265^2 .

It is a cyclic number.

It is not a de Polignac number, because 257661521 - 2²² = 253467217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (257661511) 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, 9910046 + ... + 9910071.

It is an arithmetic number, because the mean of its divisors is an integer number (69370413).

Almost surely, 2^257661521 is an apocalyptic number.

It is an amenable number.

257661521 is a deficient number, since it is larger than the sum of its proper divisors (19820131).

257661521 is a wasteful number, since it uses less digits than its factorization.

257661521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19820130.

The product of its digits is 25200, while the sum is 35.

The square root of 257661521 is about 16051.8385551313. The cubic root of 257661521 is about 636.3311575576.

The spelling of 257661521 in words is "two hundred fifty-seven million, six hundred sixty-one thousand, five hundred twenty-one".