1668517857 has 24 divisors (see below), whose sum is σ = 2489244264. Its totient is φ = 1076385024.

The previous prime is 1668517843. The next prime is 1668517859. The reversal of 1668517857 is 7587158661.

1668517857 is a `hidden beast` number, since 16 + 68 + 517 + 8 + 57 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 165482496 + 1503035361 = 12864^2 + 38769^2 .

It is not a de Polignac number, because 1668517857 - 2⁶ = 1668517793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1668517859) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10863 + ... + 58779.

It is an arithmetic number, because the mean of its divisors is an integer number (103718511).

Almost surely, 2^1668517857 is an apocalyptic number.

It is an amenable number.

1668517857 is a deficient number, since it is larger than the sum of its proper divisors (820726407).

1668517857 is a wasteful number, since it uses less digits than its factorization.

1668517857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48049 (or 48046 counting only the distinct ones).

The product of its digits is 2822400, while the sum is 54.

The square root of 1668517857 is about 40847.4951129197. The cubic root of 1668517857 is about 1186.0699048419.

The spelling of 1668517857 in words is "one billion, six hundred sixty-eight million, five hundred seventeen thousand, eight hundred fifty-seven".