21211219973 has 2 divisors, whose sum is σ = 21211219974. Its totient is φ = 21211219972.

The previous prime is 21211219963. The next prime is 21211220021. The reversal of 21211219973 is 37991211212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15885577444 + 5325642529 = 126038^2 + 72977^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211219973 - 2¹⁸ = 21210957829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211219963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605609986 + 10605609987.

It is an arithmetic number, because the mean of its divisors is an integer number (10605609987).

Almost surely, 2^21211219973 is an apocalyptic number.

It is an amenable number.

21211219973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211219973 is an equidigital number, since it uses as much as digits as its factorization.

21211219973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13608, while the sum is 38.

The spelling of 21211219973 in words is "twenty-one billion, two hundred eleven million, two hundred nineteen thousand, nine hundred seventy-three".