21456306 has 32 divisors (see below), whose sum is σ = 48342720. Its totient is φ = 7052832.

The previous prime is 21456289. The next prime is 21456311. The reversal of 21456306 is 60365412.

21456306 is a `hidden beast` number, since 21 + 4 + 5 + 630 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21456306.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1221 + ... + 6663.

It is an arithmetic number, because the mean of its divisors is an integer number (1510710).

Almost surely, 2^21456306 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21456306, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24171360).

21456306 is an abundant number, since it is smaller than the sum of its proper divisors (26886414).

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

21456306 is a wasteful number, since it uses less digits than its factorization.

21456306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5527 (or 5521 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 21456306 is about 4632.0952062754. The cubic root of 21456306 is about 277.8763920918.

The spelling of 21456306 in words is "twenty-one million, four hundred fifty-six thousand, three hundred six".