257981661 has 24 divisors (see below), whose sum is σ = 427137984. Its totient is φ = 146980800.

The previous prime is 257981629. The next prime is 257981671. The reversal of 257981661 is 166189752.

257981661 is a `hidden beast` number, since 2 + 579 + 8 + 16 + 61 = 666.

It is not a de Polignac number, because 257981661 - 2⁵ = 257981629 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257981611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15961 + ... + 27761.

It is an arithmetic number, because the mean of its divisors is an integer number (17797416).

Almost surely, 2^257981661 is an apocalyptic number.

257981661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

257981661 is a deficient number, since it is larger than the sum of its proper divisors (169156323).

257981661 is a wasteful number, since it uses less digits than its factorization.

257981661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12161 (or 12158 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 257981661 is about 16061.8075259293. The cubic root of 257981661 is about 636.5945919829.

The spelling of 257981661 in words is "two hundred fifty-seven million, nine hundred eighty-one thousand, six hundred sixty-one".