21426768 has 140 divisors (see below), whose sum is σ = 68308128. Its totient is φ = 6454080.

The previous prime is 21426767. The next prime is 21426773. The reversal of 21426768 is 86762412.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21426763) 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 27 ways as a sum of consecutive naturals, for example, 128221 + ... + 128387.

Almost surely, 2^21426768 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21426768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34154064).

21426768 is an abundant number, since it is smaller than the sum of its proper divisors (46881360).

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

21426768 is a wasteful number, since it uses less digits than its factorization.

21426768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204 (or 183 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21426768 is about 4628.9057022152. The cubic root of 21426768 is about 277.7488199265.

The spelling of 21426768 in words is "twenty-one million, four hundred twenty-six thousand, seven hundred sixty-eight".