2179172561 has 4 divisors (see below), whose sum is σ = 2179268532. Its totient is φ = 2179076592.

The previous prime is 2179172551. The next prime is 2179172587. The reversal of 2179172561 is 1652719712.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 2021041936 + 158130625 = 44956^2 + 12575^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2179172561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2179172551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7331 + ... + 66423.

It is an arithmetic number, because the mean of its divisors is an integer number (544817133).

Almost surely, 2^2179172561 is an apocalyptic number.

It is an amenable number.

2179172561 is a deficient number, since it is larger than the sum of its proper divisors (95971).

2179172561 is an equidigital number, since it uses as much as digits as its factorization.

2179172561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95970.

The product of its digits is 52920, while the sum is 41.

The square root of 2179172561 is about 46681.6083806032. The cubic root of 2179172561 is about 1296.4741858988.

The spelling of 2179172561 in words is "two billion, one hundred seventy-nine million, one hundred seventy-two thousand, five hundred sixty-one".