21993073 has 2 divisors, whose sum is σ = 21993074. Its totient is φ = 21993072.

The previous prime is 21993071. The next prime is 21993079. The reversal of 21993073 is 37039912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21372129 + 620944 = 4623^2 + 788^2 .

It is a cyclic number.

It is not a de Polignac number, because 21993073 - 2¹ = 21993071 is a prime.

Together with 21993071, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21993071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10996536 + 10996537.

It is an arithmetic number, because the mean of its divisors is an integer number (10996537).

Almost surely, 2^21993073 is an apocalyptic number.

It is an amenable number.

21993073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21993073 is an equidigital number, since it uses as much as digits as its factorization.

21993073 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 21993073 is about 4689.6772810077. The cubic root of 21993073 is about 280.1745213020.

The spelling of 21993073 in words is "twenty-one million, nine hundred ninety-three thousand, seventy-three".