1611915561 has 12 divisors (see below), whose sum is σ = 2330478592. Its totient is φ = 1073615256.

The previous prime is 1611915551. The next prime is 1611915581. The reversal of 1611915561 is 1655191161.

It is a happy number.

1611915561 is a `hidden beast` number, since 1 + 6 + 1 + 1 + 91 + 5 + 561 = 666.

It is not a de Polignac number, because 1611915561 - 2¹⁵ = 1611882793 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1611915541) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 72601 + ... + 92166.

Almost surely, 2^1611915561 is an apocalyptic number.

It is an amenable number.

1611915561 is a deficient number, since it is larger than the sum of its proper divisors (718563031).

1611915561 is a wasteful number, since it uses less digits than its factorization.

1611915561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165860 (or 165857 counting only the distinct ones).

The product of its digits is 8100, while the sum is 36.

The square root of 1611915561 is about 40148.6682344508. The cubic root of 1611915561 is about 1172.5033600709.

The spelling of 1611915561 in words is "one billion, six hundred eleven million, nine hundred fifteen thousand, five hundred sixty-one".