21985095221 has 2 divisors, whose sum is σ = 21985095222. Its totient is φ = 21985095220.

The previous prime is 21985095163. The next prime is 21985095229. The reversal of 21985095221 is 12259058912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17480806225 + 4504288996 = 132215^2 + 67114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21985095221 - 2¹⁸ = 21984833077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21985095229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10992547610 + 10992547611.

It is an arithmetic number, because the mean of its divisors is an integer number (10992547611).

Almost surely, 2^21985095221 is an apocalyptic number.

It is an amenable number.

21985095221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21985095221 is an equidigital number, since it uses as much as digits as its factorization.

21985095221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 129600, while the sum is 44.

The spelling of 21985095221 in words is "twenty-one billion, nine hundred eighty-five million, ninety-five thousand, two hundred twenty-one".