21220999973 has 2 divisors, whose sum is σ = 21220999974. Its totient is φ = 21220999972.

The previous prime is 21220999963. The next prime is 21221000027. The reversal of 21220999973 is 37999902212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10902909889 + 10318090084 = 104417^2 + 101578^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220999973 - 2¹⁰ = 21220998949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220999913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610499986 + 10610499987.

It is an arithmetic number, because the mean of its divisors is an integer number (10610499987).

Almost surely, 2^21220999973 is an apocalyptic number.

It is an amenable number.

21220999973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220999973 is an equidigital number, since it uses as much as digits as its factorization.

21220999973 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1102248, while the sum is 53.

The spelling of 21220999973 in words is "twenty-one billion, two hundred twenty million, nine hundred ninety-nine thousand, nine hundred seventy-three".