15993221391906 has 64 divisors (see below), whose sum is σ = 36415502484480. Its totient is φ = 4635199736640.

The previous prime is 15993221391841. The next prime is 15993221391913. The reversal of 15993221391906 is 60919312239951.

15993221391906 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 15993221391906.

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, 13144740 + ... + 14309808.

It is an arithmetic number, because the mean of its divisors is an integer number (568992226320).

Almost surely, 2^{15993221391906} is an apocalyptic number.

15993221391906 is an abundant number, since it is smaller than the sum of its proper divisors (20422281092574).

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

15993221391906 is a wasteful number, since it uses less digits than its factorization.

15993221391906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1174151.

The product of its (nonzero) digits is 7085880, while the sum is 60.

The spelling of 15993221391906 in words is "fifteen trillion, nine hundred ninety-three billion, two hundred twenty-one million, three hundred ninety-one thousand, nine hundred six".