21439255 has 4 divisors (see below), whose sum is σ = 25727112. Its totient is φ = 17151400.

The previous prime is 21439237. The next prime is 21439273. The reversal of 21439255 is 55293412.

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

It is an interprime number because it is at equal distance from previous prime (21439237) and next prime (21439273).

It is not a de Polignac number, because 21439255 - 2⁷ = 21439127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2143921 + ... + 2143930.

It is an arithmetic number, because the mean of its divisors is an integer number (6431778).

Almost surely, 2^21439255 is an apocalyptic number.

21439255 is a deficient number, since it is larger than the sum of its proper divisors (4287857).

21439255 is an equidigital number, since it uses as much as digits as its factorization.

21439255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4287856.

The product of its digits is 10800, while the sum is 31.

The square root of 21439255 is about 4630.2543126701. The cubic root of 21439255 is about 277.8027645375.

The spelling of 21439255 in words is "twenty-one million, four hundred thirty-nine thousand, two hundred fifty-five".