21222978181 has 4 divisors (see below), whose sum is σ = 21461438700. Its totient is φ = 20984517664.

The previous prime is 21222978173. The next prime is 21222978221. The reversal of 21222978181 is 18187922212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10851388900 + 10371589281 = 104170^2 + 101841^2 .

It is a cyclic number.

It is not a de Polignac number, because 21222978181 - 2³ = 21222978173 is a prime.

It is a super-2 number, since 2×21222978181² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222978121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119230126 + ... + 119230303.

It is an arithmetic number, because the mean of its divisors is an integer number (5365359675).

Almost surely, 2^21222978181 is an apocalyptic number.

It is an amenable number.

21222978181 is a deficient number, since it is larger than the sum of its proper divisors (238460519).

21222978181 is an equidigital number, since it uses as much as digits as its factorization.

21222978181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238460518.

The product of its digits is 64512, while the sum is 43.

The spelling of 21222978181 in words is "twenty-one billion, two hundred twenty-two million, nine hundred seventy-eight thousand, one hundred eighty-one".