1999808657 has 8 divisors (see below), whose sum is σ = 2493268032. Its totient is φ = 1558292400.

The previous prime is 1999808641. The next prime is 1999808731. The reversal of 1999808657 is 7568089991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1999808657 - 2⁴ = 1999808641 is a prime.

It is a super-2 number, since 2×1999808657² = 7998469329224287298, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1999808657.

It is not an unprimeable number, because it can be changed into a prime (1999808627) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12985694 + ... + 12985847.

It is an arithmetic number, because the mean of its divisors is an integer number (311658504).

Almost surely, 2^1999808657 is an apocalyptic number.

It is an amenable number.

1999808657 is a deficient number, since it is larger than the sum of its proper divisors (493459375).

1999808657 is a wasteful number, since it uses less digits than its factorization.

1999808657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25971559.

The product of its (nonzero) digits is 9797760, while the sum is 62.

The square root of 1999808657 is about 44719.2202190512. The cubic root of 1999808657 is about 1259.8808691012.

The spelling of 1999808657 in words is "one billion, nine hundred ninety-nine million, eight hundred eight thousand, six hundred fifty-seven".