21137939 has 8 divisors (see below), whose sum is σ = 21939072. Its totient is φ = 20344320.

The previous prime is 21137929. The next prime is 21137959. The reversal of 21137939 is 93973112.

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 21137939 - 2⁴ = 21137923 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21137899 and 21137908.

It is not an unprimeable number, because it can be changed into a prime (21137929) 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, 4217 + ... + 7749.

It is an arithmetic number, because the mean of its divisors is an integer number (2742384).

Almost surely, 2^21137939 is an apocalyptic number.

21137939 is a deficient number, since it is larger than the sum of its proper divisors (801133).

21137939 is a wasteful number, since it uses less digits than its factorization.

21137939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3757.

The product of its digits is 10206, while the sum is 35.

The square root of 21137939 is about 4597.6014398815. The cubic root of 21137939 is about 276.4951684685.

The spelling of 21137939 in words is "twenty-one million, one hundred thirty-seven thousand, nine hundred thirty-nine".