21236673 has 4 divisors (see below), whose sum is σ = 28315568. Its totient is φ = 14157780.

The previous prime is 21236669. The next prime is 21236687. The reversal of 21236673 is 37663212.

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.

It is not a de Polignac number, because 21236673 - 2² = 21236669 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21236673.

It is not an unprimeable number, because it can be changed into a prime (21236653) 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, 3539443 + ... + 3539448.

It is an arithmetic number, because the mean of its divisors is an integer number (7078892).

Almost surely, 2^21236673 is an apocalyptic number.

It is an amenable number.

21236673 is a deficient number, since it is larger than the sum of its proper divisors (7078895).

21236673 is an equidigital number, since it uses as much as digits as its factorization.

21236673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7078894.

The product of its digits is 9072, while the sum is 30.

The square root of 21236673 is about 4608.3264858298. The cubic root of 21236673 is about 276.9249971792.

Adding to 21236673 its reverse (37663212), we get a palindrome (58899885).

The spelling of 21236673 in words is "twenty-one million, two hundred thirty-six thousand, six hundred seventy-three".