15640 has 32 divisors (see below), whose sum is σ = 38880. Its totient is φ = 5632.

The previous prime is 15629. The next prime is 15641. The reversal of 15640 is 4651.

15640 = 25² + 26² + ... + 39².

15640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

15640 is an undulating number in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 669 + ... + 691.

It is an arithmetic number, because the mean of its divisors is an integer number (1215).

2¹⁵⁶⁴⁰ is an apocalyptic number.

15640 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 15640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19440).

15640 is an abundant number, since it is smaller than the sum of its proper divisors (23240).

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

15640 is a wasteful number, since it uses less digits than its factorization.

15640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 15640 is about 125.0599856069. The cubic root of 15640 is about 25.0079974414.

It can be divided in two parts, 156 and 40, that added together give a square (196 = 14²).

The spelling of 15640 in words is "fifteen thousand, six hundred forty".