857857661 has 2 divisors, whose sum is σ = 857857662. Its totient is φ = 857857660.

The previous prime is 857857607. The next prime is 857857669. The reversal of 857857661 is 166758758.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 548449561 + 309408100 = 23419^2 + 17590^2 .

It is a cyclic number.

It is not a de Polignac number, because 857857661 - 2⁶ = 857857597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (857857669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428928830 + 428928831.

It is an arithmetic number, because the mean of its divisors is an integer number (428928831).

Almost surely, 2^857857661 is an apocalyptic number.

It is an amenable number.

857857661 is a deficient number, since it is larger than the sum of its proper divisors (1).

857857661 is an equidigital number, since it uses as much as digits as its factorization.

857857661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2822400, while the sum is 53.

The square root of 857857661 is about 29289.2072443076. The cubic root of 857857661 is about 950.1782347024.

The spelling of 857857661 in words is "eight hundred fifty-seven million, eight hundred fifty-seven thousand, six hundred sixty-one".