21222978173 has 2 divisors, whose sum is σ = 21222978174. Its totient is φ = 21222978172.

The previous prime is 21222978167. The next prime is 21222978221. The reversal of 21222978173 is 37187922212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18960739204 + 2262238969 = 137698^2 + 47563^2 .

It is a cyclic number.

It is not a de Polignac number, because 21222978173 - 2⁸ = 21222977917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21222978373) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611489086 + 10611489087.

It is an arithmetic number, because the mean of its divisors is an integer number (10611489087).

Almost surely, 2^21222978173 is an apocalyptic number.

It is an amenable number.

21222978173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21222978173 is an equidigital number, since it uses as much as digits as its factorization.

21222978173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 169344, while the sum is 44.

The spelling of 21222978173 in words is "twenty-one billion, two hundred twenty-two million, nine hundred seventy-eight thousand, one hundred seventy-three".