1601511561 has 16 divisors (see below), whose sum is σ = 2555118720. Its totient is φ = 985545360.

The previous prime is 1601511557. The next prime is 1601511599. The reversal of 1601511561 is 1651151061.

1601511561 is a `hidden beast` number, since 1 + 601 + 5 + 1 + 1 + 56 + 1 = 666.

It is not a de Polignac number, because 1601511561 - 2² = 1601511557 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1601511661) 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, 2281005 + ... + 2281706.

It is an arithmetic number, because the mean of its divisors is an integer number (159694920).

Almost surely, 2^1601511561 is an apocalyptic number.

It is an amenable number.

1601511561 is a deficient number, since it is larger than the sum of its proper divisors (953607159).

1601511561 is a wasteful number, since it uses less digits than its factorization.

1601511561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4562733 (or 4562727 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 27.

The square root of 1601511561 is about 40018.8900520742. The cubic root of 1601511561 is about 1169.9752986238.

The spelling of 1601511561 in words is "one billion, six hundred one million, five hundred eleven thousand, five hundred sixty-one".