1601156561661 has 6 divisors (see below), whose sum is σ = 2312781700190. Its totient is φ = 1067437707768.

The previous prime is 1601156561657. The next prime is 1601156561671. The reversal of 1601156561661 is 1661656511061.

1601156561661 is a `hidden beast` number, since 1 + 6 + 0 + 11 + 565 + 6 + 16 + 61 = 666.

It can be written as a sum of positive squares in only one way, i.e., 905485464900 + 695671096761 = 951570^2 + 834069^2 .

It is not a de Polignac number, because 1601156561661 - 2² = 1601156561657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1601156561611) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 88953142306 + ... + 88953142323.

Almost surely, 2^{1601156561661} is an apocalyptic number.

It is an amenable number.

1601156561661 is a deficient number, since it is larger than the sum of its proper divisors (711625138529).

1601156561661 is a wasteful number, since it uses less digits than its factorization.

1601156561661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177906284635 (or 177906284632 counting only the distinct ones).

The product of its (nonzero) digits is 194400, while the sum is 45.

The spelling of 1601156561661 in words is "one trillion, six hundred one billion, one hundred fifty-six million, five hundred sixty-one thousand, six hundred sixty-one".