15640400 has 60 divisors (see below), whose sum is σ = 38251644. Its totient is φ = 6144000.

The previous prime is 15640379. The next prime is 15640403. The reversal of 15640400 is 404651.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 678976 + 14961424 = 824^2 + 3868^2 .

It is a super-2 number, since 2×15640400² = 489244224320000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a nialpdrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15640403) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 24080 + ... + 24720.

Almost surely, 2^15640400 is an apocalyptic number.

15640400 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 15640400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19125822).

15640400 is an abundant number, since it is smaller than the sum of its proper divisors (22611244).

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

15640400 is a wasteful number, since it uses less digits than its factorization.

15640400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 720 (or 709 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 15640400 is about 3954.7945585074. The cubic root of 15640400 is about 250.0821063646.

The spelling of 15640400 in words is "fifteen million, six hundred forty thousand, four hundred".