1999688640 has 56 divisors (see below), whose sum is σ = 6349014480. Its totient is φ = 533250048.

The previous prime is 1999688557. The next prime is 1999688651. The reversal of 1999688640 is 468869991.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1040545 + ... + 1042464.

Almost surely, 2^1999688640 is an apocalyptic number.

1999688640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1999688640 is an abundant number, since it is smaller than the sum of its proper divisors (4349325840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1999688640 is a wasteful number, since it uses less digits than its factorization.

1999688640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2083029 (or 2083019 counting only the distinct ones).

The product of its (nonzero) digits is 6718464, while the sum is 60.

The square root of 1999688640 is about 44717.8783038730. The cubic root of 1999688640 is about 1259.8556649987.

The spelling of 1999688640 in words is "one billion, nine hundred ninety-nine million, six hundred eighty-eight thousand, six hundred forty".