257187321 has 6 divisors (see below), whose sum is σ = 371492810. Its totient is φ = 171458208.

The previous prime is 257187317. The next prime is 257187349. The reversal of 257187321 is 123781752.

257187321 is a `hidden beast` number, since 2 + 571 + 87 + 3 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 235284921 + 21902400 = 15339^2 + 4680^2 .

It is not a de Polignac number, because 257187321 - 2² = 257187317 is a prime.

It is a super-2 number, since 2×257187321² = 132290636166314082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257187121) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14288176 + ... + 14288193.

Almost surely, 2^257187321 is an apocalyptic number.

It is an amenable number.

257187321 is a deficient number, since it is larger than the sum of its proper divisors (114305489).

257187321 is a wasteful number, since it uses less digits than its factorization.

257187321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28576375 (or 28576372 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 257187321 is about 16037.0608591475. The cubic root of 257187321 is about 635.9405500976.

It can be divided in two parts, 257 and 187321, that added together give a triangular number (187578 = T₆₁₂).

The spelling of 257187321 in words is "two hundred fifty-seven million, one hundred eighty-seven thousand, three hundred twenty-one".