21421239 has 8 divisors (see below), whose sum is σ = 32641920. Its totient is φ = 12240696.

The previous prime is 21421201. The next prime is 21421243. The reversal of 21421239 is 93212412.

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

It is not a de Polignac number, because 21421239 - 2¹⁷ = 21290167 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 510009 + ... + 510050.

It is an arithmetic number, because the mean of its divisors is an integer number (4080240).

Almost surely, 2^21421239 is an apocalyptic number.

21421239 is a deficient number, since it is larger than the sum of its proper divisors (11220681).

21421239 is a wasteful number, since it uses less digits than its factorization.

21421239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1020069.

The product of its digits is 864, while the sum is 24.

The square root of 21421239 is about 4628.3084382958. The cubic root of 21421239 is about 277.7249276105.

It can be divided in two parts, 2 and 1421239, that added together give a palindrome (1421241).

The spelling of 21421239 in words is "twenty-one million, four hundred twenty-one thousand, two hundred thirty-nine".