21389839 has 8 divisors (see below), whose sum is σ = 23495040. Its totient is φ = 19382616.

The previous prime is 21389831. The next prime is 21389843. The reversal of 21389839 is 93898312.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21389839 - 2³ = 21389831 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21389795 and 21389804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21389831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24037 + ... + 24910.

It is an arithmetic number, because the mean of its divisors is an integer number (2936880).

Almost surely, 2^21389839 is an apocalyptic number.

21389839 is a deficient number, since it is larger than the sum of its proper divisors (2105201).

21389839 is a wasteful number, since it uses less digits than its factorization.

21389839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48989.

The product of its digits is 93312, while the sum is 43.

The square root of 21389839 is about 4624.9150262464. The cubic root of 21389839 is about 277.5891616204.

The spelling of 21389839 in words is "twenty-one million, three hundred eighty-nine thousand, eight hundred thirty-nine".