21682216901 has 2 divisors, whose sum is σ = 21682216902. Its totient is φ = 21682216900.

The previous prime is 21682216877. The next prime is 21682216903. The reversal of 21682216901 is 10961228612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11486266276 + 10195950625 = 107174^2 + 100975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21682216901 is a prime.

It is a Sophie Germain prime.

Together with 21682216903, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21682216903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10841108450 + 10841108451.

It is an arithmetic number, because the mean of its divisors is an integer number (10841108451).

Almost surely, 2^21682216901 is an apocalyptic number.

It is an amenable number.

21682216901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21682216901 is an equidigital number, since it uses as much as digits as its factorization.

21682216901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 38.

The spelling of 21682216901 in words is "twenty-one billion, six hundred eighty-two million, two hundred sixteen thousand, nine hundred one".