15661990 has 8 divisors (see below), whose sum is σ = 28191600. Its totient is φ = 6264792.

The previous prime is 15661973. The next prime is 15661991. The reversal of 15661990 is 9916651.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15661991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 783090 + ... + 783109.

It is an arithmetic number, because the mean of its divisors is an integer number (3523950).

Almost surely, 2^15661990 is an apocalyptic number.

15661990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

15661990 is a deficient number, since it is larger than the sum of its proper divisors (12529610).

15661990 is a wasteful number, since it uses less digits than its factorization.

15661990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1566206.

The product of its (nonzero) digits is 14580, while the sum is 37.

The square root of 15661990 is about 3957.5232153457. The cubic root of 15661990 is about 250.1971245268.

The spelling of 15661990 in words is "fifteen million, six hundred sixty-one thousand, nine hundred ninety".