21268639 has 8 divisors (see below), whose sum is σ = 24370848. Its totient is φ = 18182400.

The previous prime is 21268631. The next prime is 21268661. The reversal of 21268639 is 93686212.

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 21268639 - 2³ = 21268631 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21268598 and 21268607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21268631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 982 + ... + 6595.

It is an arithmetic number, because the mean of its divisors is an integer number (3046356).

Almost surely, 2^21268639 is an apocalyptic number.

21268639 is a deficient number, since it is larger than the sum of its proper divisors (3102209).

21268639 is an equidigital number, since it uses as much as digits as its factorization.

21268639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7985.

The product of its digits is 31104, while the sum is 37.

The square root of 21268639 is about 4611.7934689229. The cubic root of 21268639 is about 277.0638724581.

The spelling of 21268639 in words is "twenty-one million, two hundred sixty-eight thousand, six hundred thirty-nine".