21031239 has 8 divisors (see below), whose sum is σ = 28065520. Its totient is φ = 14008896.

The previous prime is 21031229. The next prime is 21031253. The reversal of 21031239 is 93213012.

It is a happy number.

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

It is not a de Polignac number, because 21031239 - 2⁷ = 21031111 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 (21031229) 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, 2649 + ... + 7005.

It is an arithmetic number, because the mean of its divisors is an integer number (3508190).

Almost surely, 2^21031239 is an apocalyptic number.

21031239 is a deficient number, since it is larger than the sum of its proper divisors (7034281).

21031239 is a wasteful number, since it uses less digits than its factorization.

21031239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5969.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 21031239 is about 4585.9828826545. The cubic root of 21031239 is about 276.0291530852.

The spelling of 21031239 in words is "twenty-one million, thirty-one thousand, two hundred thirty-nine".