21037239 has 12 divisors (see below), whose sum is σ = 31512936. Its totient is φ = 14024664.

The previous prime is 21037231. The next prime is 21037241. The reversal of 21037239 is 93273012.

It is not a de Polignac number, because 21037239 - 2³ = 21037231 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21037231) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43044 + ... + 43529.

It is an arithmetic number, because the mean of its divisors is an integer number (2626078).

Almost surely, 2^21037239 is an apocalyptic number.

21037239 is a deficient number, since it is larger than the sum of its proper divisors (10475697).

21037239 is an frugal number, since it uses more digits than its factorization.

21037239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86588 (or 86576 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 27.

The square root of 21037239 is about 4586.6370032956. The cubic root of 21037239 is about 276.0554000322.

The spelling of 21037239 in words is "twenty-one million, thirty-seven thousand, two hundred thirty-nine".