2172909881 has 2 divisors, whose sum is σ = 2172909882. Its totient is φ = 2172909880.

The previous prime is 2172909857. The next prime is 2172909899. The reversal of 2172909881 is 1889092712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1926419881 + 246490000 = 43891^2 + 15700^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2172909881 is a prime.

It is a super-2 number, since 2×2172909881² = 9443074701894868322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2172909821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1086454940 + 1086454941.

It is an arithmetic number, because the mean of its divisors is an integer number (1086454941).

Almost surely, 2^2172909881 is an apocalyptic number.

It is an amenable number.

2172909881 is a deficient number, since it is larger than the sum of its proper divisors (1).

2172909881 is an equidigital number, since it uses as much as digits as its factorization.

2172909881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 47.

The square root of 2172909881 is about 46614.4814515833. The cubic root of 2172909881 is about 1295.2310239138.

The spelling of 2172909881 in words is "two billion, one hundred seventy-two million, nine hundred nine thousand, eight hundred eighty-one".