15681990 has 64 divisors (see below), whose sum is σ = 40388544. Its totient is φ = 3883008.

The previous prime is 15681989. The next prime is 15681997. The reversal of 15681990 is 9918651.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15681997) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 49312 + ... + 49628.

It is an arithmetic number, because the mean of its divisors is an integer number (631071).

Almost surely, 2^15681990 is an apocalyptic number.

15681990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 15681990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20194272).

15681990 is an abundant number, since it is smaller than the sum of its proper divisors (24706554).

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

15681990 is a wasteful number, since it uses less digits than its factorization.

15681990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 441.

The product of its (nonzero) digits is 19440, while the sum is 39.

The square root of 15681990 is about 3960.0492421181. The cubic root of 15681990 is about 250.3035778793.

The spelling of 15681990 in words is "fifteen million, six hundred eighty-one thousand, nine hundred ninety".