15991040 has 108 divisors (see below), whose sum is σ = 42623532. Its totient is φ = 5713920.

The previous prime is 15991037. The next prime is 15991097. The reversal of 15991040 is 4019951.

It can be written as a sum of positive squares in 2 ways, for example, as 3936256 + 12054784 = 1984^2 + 3472^2 .

It is a junction number, because it is equal to n+sod(n) for n = 15990994 and 15991012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 515825 + ... + 515855.

Almost surely, 2^15991040 is an apocalyptic number.

15991040 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 15991040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21311766).

15991040 is an abundant number, since it is smaller than the sum of its proper divisors (26632492).

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

15991040 is an equidigital number, since it uses as much as digits as its factorization.

15991040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96 (or 51 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 15991040 is about 3998.8798431561. The cubic root of 15991040 is about 251.9371641435.

The spelling of 15991040 in words is "fifteen million, nine hundred ninety-one thousand, forty".