15999900 has 144 divisors (see below), whose sum is σ = 55829760. Its totient is φ = 3456000.

The previous prime is 15999883. The next prime is 15999923. The reversal of 15999900 is 999951.

15999900 is digitally balanced in base 2 and base 8, because in such bases it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (42).

15999900 is strictly pandigital in base 8.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 39700 + ... + 40100.

Almost surely, 2^15999900 is an apocalyptic number.

15999900 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 15999900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27914880).

15999900 is an abundant number, since it is smaller than the sum of its proper divisors (39829860).

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

15999900 is a wasteful number, since it uses less digits than its factorization.

15999900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444 (or 437 counting only the distinct ones).

The product of its (nonzero) digits is 32805, while the sum is 42.

The square root of 15999900 is about 3999.9874999805. The cubic root of 15999900 is about 251.9836850108.

The spelling of 15999900 in words is "fifteen million, nine hundred ninety-nine thousand, nine hundred".