21443839 has 6 divisors (see below), whose sum is σ = 21757040. Its totient is φ = 21131760.

The previous prime is 21443827. The next prime is 21443881. The reversal of 21443839 is 93834412.

21443839 = T₄₄₀ + T₄₄₁ + ... + T₅₉₇.

It is not a de Polignac number, because 21443839 - 2⁷ = 21443711 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443809) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 40899 + ... + 41419.

Almost surely, 2^21443839 is an apocalyptic number.

21443839 is a deficient number, since it is larger than the sum of its proper divisors (313201).

21443839 is an frugal number, since it uses more digits than its factorization.

21443839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121 (or 600 counting only the distinct ones).

The product of its digits is 20736, while the sum is 34.

The square root of 21443839 is about 4630.7492914214. The cubic root of 21443839 is about 277.8225624444.

The spelling of 21443839 in words is "twenty-one million, four hundred forty-three thousand, eight hundred thirty-nine".