257857661 has 2 divisors, whose sum is σ = 257857662. Its totient is φ = 257857660.

The previous prime is 257857643. The next prime is 257857679. The reversal of 257857661 is 166758752.

It is a balanced prime because it is at equal distance from previous prime (257857643) and next prime (257857679).

It can be written as a sum of positive squares in only one way, i.e., 130393561 + 127464100 = 11419^2 + 11290^2 .

It is a cyclic number.

It is not a de Polignac number, because 257857661 - 2¹⁰ = 257856637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257857861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128928830 + 128928831.

It is an arithmetic number, because the mean of its divisors is an integer number (128928831).

Almost surely, 2^257857661 is an apocalyptic number.

It is an amenable number.

257857661 is a deficient number, since it is larger than the sum of its proper divisors (1).

257857661 is an equidigital number, since it uses as much as digits as its factorization.

257857661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 705600, while the sum is 47.

The square root of 257857661 is about 16057.9469733836. The cubic root of 257857661 is about 636.4925816569.

The spelling of 257857661 in words is "two hundred fifty-seven million, eight hundred fifty-seven thousand, six hundred sixty-one".