21993233 has 2 divisors, whose sum is σ = 21993234. Its totient is φ = 21993232.

The previous prime is 21993217. The next prime is 21993239. The reversal of 21993233 is 33239912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21827584 + 165649 = 4672^2 + 407^2 .

It is a cyclic number.

It is not a de Polignac number, because 21993233 - 2⁴ = 21993217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21993233.

It is not a weakly prime, because it can be changed into another prime (21993239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10996616 + 10996617.

It is an arithmetic number, because the mean of its divisors is an integer number (10996617).

Almost surely, 2^21993233 is an apocalyptic number.

It is an amenable number.

21993233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21993233 is an equidigital number, since it uses as much as digits as its factorization.

21993233 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8748, while the sum is 32.

The square root of 21993233 is about 4689.6943397198. The cubic root of 21993233 is about 280.1752007252.

The spelling of 21993233 in words is "twenty-one million, nine hundred ninety-three thousand, two hundred thirty-three".