21195839 has 16 divisors (see below), whose sum is σ = 25235520. Its totient is φ = 17418240.

The previous prime is 21195829. The next prime is 21195841. The reversal of 21195839 is 93859112.

It is not a de Polignac number, because 21195839 - 2¹² = 21191743 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 (21195829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38909 + ... + 39449.

It is an arithmetic number, because the mean of its divisors is an integer number (1577220).

Almost surely, 2^21195839 is an apocalyptic number.

21195839 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21195839 is a deficient number, since it is larger than the sum of its proper divisors (4039681).

21195839 is a wasteful number, since it uses less digits than its factorization.

21195839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 770.

The product of its digits is 19440, while the sum is 38.

The square root of 21195839 is about 4603.8938953890. The cubic root of 21195839 is about 276.7473922918.

The spelling of 21195839 in words is "twenty-one million, one hundred ninety-five thousand, eight hundred thirty-nine".