21443999 has 2 divisors, whose sum is σ = 21444000. Its totient is φ = 21443998.

The previous prime is 21443941. The next prime is 21444011. The reversal of 21443999 is 99934412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21443999 - 2²⁰ = 20395423 is a prime.

It is a super-2 number, since 2×21443999² = 919690186224002, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21443099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721999 + 10722000.

It is an arithmetic number, because the mean of its divisors is an integer number (10722000).

Almost surely, 2^21443999 is an apocalyptic number.

21443999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21443999 is an equidigital number, since it uses as much as digits as its factorization.

21443999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69984, while the sum is 41.

The square root of 21443999 is about 4630.7665672111. The cubic root of 21443999 is about 277.8232534199.

The spelling of 21443999 in words is "twenty-one million, four hundred forty-three thousand, nine hundred ninety-nine".