21420222997 has 2 divisors, whose sum is σ = 21420222998. Its totient is φ = 21420222996.

The previous prime is 21420222919. The next prime is 21420223009. The reversal of 21420222997 is 79922202412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18932108836 + 2488114161 = 137594^2 + 49881^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21420222997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21420222097) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710111498 + 10710111499.

It is an arithmetic number, because the mean of its divisors is an integer number (10710111499).

Almost surely, 2^21420222997 is an apocalyptic number.

It is an amenable number.

21420222997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420222997 is an equidigital number, since it uses as much as digits as its factorization.

21420222997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 40.

The spelling of 21420222997 in words is "twenty-one billion, four hundred twenty million, two hundred twenty-two thousand, nine hundred ninety-seven".