21213320291 has 2 divisors, whose sum is σ = 21213320292. Its totient is φ = 21213320290.

The previous prime is 21213320237. The next prime is 21213320329. The reversal of 21213320291 is 19202331212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213320291 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21213320291.

It is not a weakly prime, because it can be changed into another prime (21213320221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606660145 + 10606660146.

It is an arithmetic number, because the mean of its divisors is an integer number (10606660146).

Almost surely, 2^21213320291 is an apocalyptic number.

21213320291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213320291 is an equidigital number, since it uses as much as digits as its factorization.

21213320291 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 26.

The spelling of 21213320291 in words is "twenty-one billion, two hundred thirteen million, three hundred twenty thousand, two hundred ninety-one".