21125839 has 8 divisors (see below), whose sum is σ = 24210560. Its totient is φ = 18057816.

The previous prime is 21125803. The next prime is 21125843. The reversal of 21125839 is 93852112.

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

It is not a de Polignac number, because 21125839 - 2⁷ = 21125711 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21125839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1329 + ... + 6634.

It is an arithmetic number, because the mean of its divisors is an integer number (3026320).

Almost surely, 2^21125839 is an apocalyptic number.

21125839 is a deficient number, since it is larger than the sum of its proper divisors (3084721).

21125839 is an equidigital number, since it uses as much as digits as its factorization.

21125839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8349.

The product of its digits is 4320, while the sum is 31.

The square root of 21125839 is about 4596.2853479739. The cubic root of 21125839 is about 276.4424003137.

The spelling of 21125839 in words is "twenty-one million, one hundred twenty-five thousand, eight hundred thirty-nine".