2172106561 has 4 divisors (see below), whose sum is σ = 2180760624. Its totient is φ = 2163452500.

The previous prime is 2172106513. The next prime is 2172106577. The reversal of 2172106561 is 1656012712.

2172106561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2172106561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2172106511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4326655 + ... + 4327156.

It is an arithmetic number, because the mean of its divisors is an integer number (545190156).

Almost surely, 2^2172106561 is an apocalyptic number.

It is an amenable number.

2172106561 is a deficient number, since it is larger than the sum of its proper divisors (8654063).

2172106561 is an equidigital number, since it uses as much as digits as its factorization.

2172106561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8654062.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 2172106561 is about 46605.8640194557. The cubic root of 2172106561 is about 1295.0713895539.

The spelling of 2172106561 in words is "two billion, one hundred seventy-two million, one hundred six thousand, five hundred sixty-one".