21920693 has 2 divisors, whose sum is σ = 21920694. Its totient is φ = 21920692.

The previous prime is 21920681. The next prime is 21920711. The reversal of 21920693 is 39602912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21696964 + 223729 = 4658^2 + 473^2 .

It is a cyclic number.

It is not a de Polignac number, because 21920693 - 2¹⁰ = 21919669 is a prime.

It is a Sophie Germain 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 (21920653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10960346 + 10960347.

It is an arithmetic number, because the mean of its divisors is an integer number (10960347).

Almost surely, 2^21920693 is an apocalyptic number.

It is an amenable number.

21920693 is a deficient number, since it is larger than the sum of its proper divisors (1).

21920693 is an equidigital number, since it uses as much as digits as its factorization.

21920693 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 21920693 is about 4681.9539724350. The cubic root of 21920693 is about 279.8668286790.

The spelling of 21920693 in words is "twenty-one million, nine hundred twenty thousand, six hundred ninety-three".