2161020661 has 8 divisors (see below), whose sum is σ = 2260831104. Its totient is φ = 2063453280.

The previous prime is 2161020643. The next prime is 2161020707. The reversal of 2161020661 is 1660201612.

2161020661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2161020661 - 2⁹ = 2161020149 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 (2161021661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 558795 + ... + 562648.

It is an arithmetic number, because the mean of its divisors is an integer number (282603888).

Almost surely, 2^2161020661 is an apocalyptic number.

It is an amenable number.

2161020661 is a deficient number, since it is larger than the sum of its proper divisors (99810443).

2161020661 is a wasteful number, since it uses less digits than its factorization.

2161020661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121531.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 2161020661 is about 46486.7794216807. The cubic root of 2161020661 is about 1292.8643882044.

The spelling of 2161020661 in words is "two billion, one hundred sixty-one million, twenty thousand, six hundred sixty-one".