21392837 has 4 divisors (see below), whose sum is σ = 21402720. Its totient is φ = 21382956.

The previous prime is 21392779. The next prime is 21392843. The reversal of 21392837 is 73829312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, 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 21392837 - 2⁶ = 21392773 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21392797 and 21392806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21392237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 137 + ... + 6542.

It is an arithmetic number, because the mean of its divisors is an integer number (5350680).

Almost surely, 2^21392837 is an apocalyptic number.

It is an amenable number.

21392837 is a deficient number, since it is larger than the sum of its proper divisors (9883).

21392837 is an equidigital number, since it uses as much as digits as its factorization.

21392837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9882.

The product of its digits is 18144, while the sum is 35.

The square root of 21392837 is about 4625.2391289532. The cubic root of 21392837 is about 277.6021299809.

The spelling of 21392837 in words is "twenty-one million, three hundred ninety-two thousand, eight hundred thirty-seven".