21443899 has 4 divisors (see below), whose sum is σ = 21465136. Its totient is φ = 21422664.

The previous prime is 21443893. The next prime is 21443911. The reversal of 21443899 is 99834412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21443899 - 2¹³ = 21435707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21443893) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9024 + ... + 11149.

It is an arithmetic number, because the mean of its divisors is an integer number (5366284).

Almost surely, 2^21443899 is an apocalyptic number.

21443899 is a deficient number, since it is larger than the sum of its proper divisors (21237).

21443899 is a wasteful number, since it uses less digits than its factorization.

21443899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21236.

The product of its digits is 62208, while the sum is 40.

The square root of 21443899 is about 4630.7557698501. The cubic root of 21443899 is about 277.8228215606.

The spelling of 21443899 in words is "twenty-one million, four hundred forty-three thousand, eight hundred ninety-nine".