15561840 has 160 divisors (see below), whose sum is σ = 56424960. Its totient is φ = 3474432.

The previous prime is 15561839. The next prime is 15561853. The reversal of 15561840 is 4816551.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 15561798 and 15561807.

It is a congruent number.

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 31 ways as a sum of consecutive naturals, for example, 99042 + ... + 99198.

It is an arithmetic number, because the mean of its divisors is an integer number (352656).

Almost surely, 2^15561840 is an apocalyptic number.

15561840 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 15561840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28212480).

15561840 is an abundant number, since it is smaller than the sum of its proper divisors (40863120).

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

15561840 is a wasteful number, since it uses less digits than its factorization.

15561840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239 (or 233 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 30.

The square root of 15561840 is about 3944.8498070269. The cubic root of 15561840 is about 249.6626917640.

The spelling of 15561840 in words is "fifteen million, five hundred sixty-one thousand, eight hundred forty".