15981840 has 240 divisors, whose sum is σ = 64460160. Its totient is φ = 3628800.

The previous prime is 15981839. The next prime is 15981851. The reversal of 15981840 is 4818951.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 15981795 and 15981804.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 105765 + ... + 105915.

It is an arithmetic number, because the mean of its divisors is an integer number (268584).

Almost surely, 2^15981840 is an apocalyptic number.

15981840 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 15981840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32230080).

15981840 is an abundant number, since it is smaller than the sum of its proper divisors (48478320).

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

15981840 is a wasteful number, since it uses less digits than its factorization.

15981840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187 (or 168 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 36.

The square root of 15981840 is about 3997.7293555217. The cubic root of 15981840 is about 251.8888398621. Note that the first 4 decimals are identical.

The spelling of 15981840 in words is "fifteen million, nine hundred eighty-one thousand, eight hundred forty".