21968818958621 has 2 divisors, whose sum is σ = 21968818958622. Its totient is φ = 21968818958620.

The previous prime is 21968818958521. The next prime is 21968818958633. The reversal of 21968818958621 is 12685981886912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20903970391396 + 1064848567225 = 4572086^2 + 1031915^2 .

It is a cyclic number.

It is not a de Polignac number, because 21968818958621 - 2¹⁰ = 21968818957597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21968818958521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10984409479310 + 10984409479311.

It is an arithmetic number, because the mean of its divisors is an integer number (10984409479311).

Almost surely, 2^{21968818958621} is an apocalyptic number.

It is an amenable number.

21968818958621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21968818958621 is an equidigital number, since it uses as much as digits as its factorization.

21968818958621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 238878720, while the sum is 74.

The spelling of 21968818958621 in words is "twenty-one trillion, nine hundred sixty-eight billion, eight hundred eighteen million, nine hundred fifty-eight thousand, six hundred twenty-one".