1561611545 has 24 divisors (see below), whose sum is σ = 2059531776. Its totient is φ = 1135937088.

The previous prime is 1561611509. The next prime is 1561611581. The reversal of 1561611545 is 5451161651.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1561611509) and next prime (1561611581).

It is not a de Polignac number, because 1561611545 - 2¹⁶ = 1561546009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 42824 + ... + 70406.

It is an arithmetic number, because the mean of its divisors is an integer number (85813824).

Almost surely, 2^1561611545 is an apocalyptic number.

It is an amenable number.

1561611545 is a deficient number, since it is larger than the sum of its proper divisors (497920231).

1561611545 is a wasteful number, since it uses less digits than its factorization.

1561611545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27681 (or 27668 counting only the distinct ones).

The product of its digits is 18000, while the sum is 35.

The square root of 1561611545 is about 39517.2309885194. The cubic root of 1561611545 is about 1160.1772284205.

The spelling of 1561611545 in words is "one billion, five hundred sixty-one million, six hundred eleven thousand, five hundred forty-five".