1561646664 has 48 divisors (see below), whose sum is σ = 4232376720. Its totient is φ = 520189920.

The previous prime is 1561646627. The next prime is 1561646683. The reversal of 1561646664 is 4666461651.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 110479 + ... + 123809.

It is an arithmetic number, because the mean of its divisors is an integer number (88174515).

Almost surely, 2^1561646664 is an apocalyptic number.

It is an amenable number.

1561646664 is an abundant number, since it is smaller than the sum of its proper divisors (2670730056).

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

1561646664 is a wasteful number, since it uses less digits than its factorization.

1561646664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14970 (or 14963 counting only the distinct ones).

The product of its digits is 622080, while the sum is 45.

The square root of 1561646664 is about 39517.6753364871. The cubic root of 1561646664 is about 1160.1859254102.

The spelling of 1561646664 in words is "one billion, five hundred sixty-one million, six hundred forty-six thousand, six hundred sixty-four".