15640440660 has 240 divisors, whose sum is σ = 54663008400. Its totient is φ = 3717052416.

The previous prime is 15640440593. The next prime is 15640440677. The reversal of 15640440660 is 6604404651.

15640440660 is a `hidden beast` number, since 1 + 5 + 640 + 4 + 4 + 0 + 6 + 6 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 223741764 + 15416698896 = 14958^2 + 124164^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 597936 + ... + 623544.

It is an arithmetic number, because the mean of its divisors is an integer number (227762535).

Almost surely, 2^15640440660 is an apocalyptic number.

15640440660 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 15640440660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27331504200).

15640440660 is an abundant number, since it is smaller than the sum of its proper divisors (39022567740).

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

15640440660 is a wasteful number, since it uses less digits than its factorization.

15640440660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25672 (or 25661 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

The spelling of 15640440660 in words is "fifteen billion, six hundred forty million, four hundred forty thousand, six hundred sixty".