21369306 has 48 divisors (see below), whose sum is σ = 52017984. Its totient is φ = 5713152.

The previous prime is 21369253. The next prime is 21369311. The reversal of 21369306 is 60396312.

It is a happy number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 123436 + ... + 123608.

It is an arithmetic number, because the mean of its divisors is an integer number (1083708).

Almost surely, 2^21369306 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21369306, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26008992).

21369306 is an abundant number, since it is smaller than the sum of its proper divisors (30648678).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21369306 is a wasteful number, since it uses less digits than its factorization.

21369306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 202 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 30.

The square root of 21369306 is about 4622.6946686970. The cubic root of 21369306 is about 277.5003100394.

The spelling of 21369306 in words is "twenty-one million, three hundred sixty-nine thousand, three hundred six".