15987840 has 128 divisors (see below), whose sum is σ = 55667520. Its totient is φ = 3870720.

The previous prime is 15987823. The next prime is 15987857. The reversal of 15987840 is 4878951.

15987840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (15987823) and next prime (15987857).

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×15987840² = 511222055731200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 15987792 and 15987801.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20742 + ... + 21498.

Almost surely, 2^15987840 is an apocalyptic number.

15987840 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 15987840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27833760).

15987840 is an abundant number, since it is smaller than the sum of its proper divisors (39679680).

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

15987840 is a wasteful number, since it uses less digits than its factorization.

15987840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 790 (or 778 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 42.

The square root of 15987840 is about 3998.4797110902. The cubic root of 15987840 is about 251.9203578005.

Subtracting from 15987840 its reverse (4878951), we obtain a square (11108889 = 3333²).

The spelling of 15987840 in words is "fifteen million, nine hundred eighty-seven thousand, eight hundred forty".