1664239857 has 16 divisors (see below), whose sum is σ = 2547363840. Its totient is φ = 946726992.

The previous prime is 1664239847. The next prime is 1664239859. The reversal of 1664239857 is 7589324661.

It is not a de Polignac number, because 1664239857 - 2⁷ = 1664239729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1664239859) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 173007 + ... + 182372.

It is an arithmetic number, because the mean of its divisors is an integer number (159210240).

Almost surely, 2^1664239857 is an apocalyptic number.

It is an amenable number.

1664239857 is a deficient number, since it is larger than the sum of its proper divisors (883123983).

1664239857 is a wasteful number, since it uses less digits than its factorization.

1664239857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355612.

The product of its digits is 2177280, while the sum is 51.

The square root of 1664239857 is about 40795.0959920430. The cubic root of 1664239857 is about 1185.0553617604.

The spelling of 1664239857 in words is "one billion, six hundred sixty-four million, two hundred thirty-nine thousand, eight hundred fifty-seven".