21031439 has 8 divisors (see below), whose sum is σ = 24708432. Its totient is φ = 17648640.

The previous prime is 21031433. The next prime is 21031457. The reversal of 21031439 is 93413012.

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 21031439 - 2⁸ = 21031183 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 (21031433) 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, 73394 + ... + 73679.

It is an arithmetic number, because the mean of its divisors is an integer number (3088554).

Almost surely, 2^21031439 is an apocalyptic number.

21031439 is a deficient number, since it is larger than the sum of its proper divisors (3676993).

21031439 is a wasteful number, since it uses less digits than its factorization.

21031439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147097.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 21031439 is about 4586.0046881790. The cubic root of 21031439 is about 276.0300280639.

The spelling of 21031439 in words is "twenty-one million, thirty-one thousand, four hundred thirty-nine".