661875857 has 2 divisors, whose sum is σ = 661875858. Its totient is φ = 661875856.

The previous prime is 661875847. The next prime is 661875941. The reversal of 661875857 is 758578166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 572932096 + 88943761 = 23936^2 + 9431^2 .

It is a cyclic number.

It is not a de Polignac number, because 661875857 - 2⁶ = 661875793 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 661875799 and 661875808.

It is not a weakly prime, because it can be changed into another prime (661875817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330937928 + 330937929.

It is an arithmetic number, because the mean of its divisors is an integer number (330937929).

Almost surely, 2^661875857 is an apocalyptic number.

It is an amenable number.

661875857 is a deficient number, since it is larger than the sum of its proper divisors (1).

661875857 is an equidigital number, since it uses as much as digits as its factorization.

661875857 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 661875857 is about 25726.9480700685. The cubic root of 661875857 is about 871.4828531869.

The spelling of 661875857 in words is "six hundred sixty-one million, eight hundred seventy-five thousand, eight hundred fifty-seven".