1561440660 has 48 divisors (see below), whose sum is σ = 4708346496. Its totient is φ = 384354432.

The previous prime is 1561440631. The next prime is 1561440677. The reversal of 1561440660 is 660441651.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1000144 + ... + 1001703.

It is an arithmetic number, because the mean of its divisors is an integer number (98090552).

Almost surely, 2^1561440660 is an apocalyptic number.

1561440660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561440660 is an abundant number, since it is smaller than the sum of its proper divisors (3146905836).

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

1561440660 is a wasteful number, since it uses less digits than its factorization.

1561440660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2001872 (or 2001870 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 1561440660 is about 39515.0687712928. The cubic root of 1561440660 is about 1160.1349080115.

Subtracting from 1561440660 its reverse (660441651), we obtain a palindrome (900999009).

The spelling of 1561440660 in words is "one billion, five hundred sixty-one million, four hundred forty thousand, six hundred sixty".