21137423 has 4 divisors (see below), whose sum is σ = 21147768. Its totient is φ = 21127080.

The previous prime is 21137419. The next prime is 21137429. The reversal of 21137423 is 32473112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21137423 - 2² = 21137419 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 (21137429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 968 + ... + 6573.

It is an arithmetic number, because the mean of its divisors is an integer number (5286942).

Almost surely, 2^21137423 is an apocalyptic number.

21137423 is a deficient number, since it is larger than the sum of its proper divisors (10345).

21137423 is an equidigital number, since it uses as much as digits as its factorization.

21137423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10344.

The product of its digits is 1008, while the sum is 23.

The square root of 21137423 is about 4597.5453233220. The cubic root of 21137423 is about 276.4929186013.

The spelling of 21137423 in words is "twenty-one million, one hundred thirty-seven thousand, four hundred twenty-three".