21993793 has 2 divisors, whose sum is σ = 21993794. Its totient is φ = 21993792.

The previous prime is 21993779. The next prime is 21993809. The reversal of 21993793 is 39739912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17783089 + 4210704 = 4217^2 + 2052^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21993793 is a prime.

It is not a weakly prime, because it can be changed into another prime (21993703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10996896 + 10996897.

It is an arithmetic number, because the mean of its divisors is an integer number (10996897).

Almost surely, 2^21993793 is an apocalyptic number.

It is an amenable number.

21993793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21993793 is an equidigital number, since it uses as much as digits as its factorization.

21993793 is an evil number, because the sum of its binary digits is even.

The product of its digits is 91854, while the sum is 43.

The square root of 21993793 is about 4689.7540447235. The cubic root of 21993793 is about 280.1775786806.

The spelling of 21993793 in words is "twenty-one million, nine hundred ninety-three thousand, seven hundred ninety-three".