21958693 has 2 divisors, whose sum is σ = 21958694. Its totient is φ = 21958692.

The previous prime is 21958691. The next prime is 21958709. The reversal of 21958693 is 39685912.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13853284 + 8105409 = 3722^2 + 2847^2 .

It is a cyclic number.

It is not a de Polignac number, because 21958693 - 2¹ = 21958691 is a prime.

Together with 21958691, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21958691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10979346 + 10979347.

It is an arithmetic number, because the mean of its divisors is an integer number (10979347).

Almost surely, 2^21958693 is an apocalyptic number.

It is an amenable number.

21958693 is a deficient number, since it is larger than the sum of its proper divisors (1).

21958693 is an equidigital number, since it uses as much as digits as its factorization.

21958693 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 43.

The square root of 21958693 is about 4686.0103499672. The cubic root of 21958693 is about 280.0284537411.

The spelling of 21958693 in words is "twenty-one million, nine hundred fifty-eight thousand, six hundred ninety-three".