1561661607 has 16 divisors (see below), whose sum is σ = 2281438080. Its totient is φ = 942324000.

The previous prime is 1561661597. The next prime is 1561661609. The reversal of 1561661607 is 7061661651.

It is not a de Polignac number, because 1561661607 - 2¹⁵ = 1561628839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561661609) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 95769 + ... + 110882.

It is an arithmetic number, because the mean of its divisors is an integer number (142589880).

Almost surely, 2^1561661607 is an apocalyptic number.

1561661607 is a deficient number, since it is larger than the sum of its proper divisors (719776473).

1561661607 is a wasteful number, since it uses less digits than its factorization.

1561661607 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206894.

The product of its (nonzero) digits is 45360, while the sum is 39.

The square root of 1561661607 is about 39517.8644033303. The cubic root of 1561661607 is about 1160.1896259065.

The spelling of 1561661607 in words is "one billion, five hundred sixty-one million, six hundred sixty-one thousand, six hundred seven".