21211021209173 has 2 divisors, whose sum is σ = 21211021209174. Its totient is φ = 21211021209172.

The previous prime is 21211021209149. The next prime is 21211021209211. The reversal of 21211021209173 is 37190212011212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17156106012049 + 4054915197124 = 4141993^2 + 2013682^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211021209173 - 2⁸ = 21211021208917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211021209113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605510604586 + 10605510604587.

It is an arithmetic number, because the mean of its divisors is an integer number (10605510604587).

Almost surely, 2^{21211021209173} is an apocalyptic number.

It is an amenable number.

21211021209173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211021209173 is an equidigital number, since it uses as much as digits as its factorization.

21211021209173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 32.

The spelling of 21211021209173 in words is "twenty-one trillion, two hundred eleven billion, twenty-one million, two hundred nine thousand, one hundred seventy-three".