1999561920 has 224 divisors, whose sum is σ = 6614403840. Its totient is φ = 511365120.

The previous prime is 1999561903. The next prime is 1999561951. The reversal of 1999561920 is 291659991.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2435110 + ... + 2435930.

Almost surely, 2^1999561920 is an apocalyptic number.

1999561920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1999561920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3307201920).

1999561920 is an abundant number, since it is smaller than the sum of its proper divisors (4614841920).

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

1999561920 is a wasteful number, since it uses less digits than its factorization.

1999561920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 943 (or 933 counting only the distinct ones).

The product of its (nonzero) digits is 393660, while the sum is 51.

The square root of 1999561920 is about 44716.4613984604. The cubic root of 1999561920 is about 1259.8290521419.

The spelling of 1999561920 in words is "one billion, nine hundred ninety-nine million, five hundred sixty-one thousand, nine hundred twenty".