21904722 has 64 divisors (see below), whose sum is σ = 56125440. Its totient is φ = 6203088.

The previous prime is 21904691. The next prime is 21904723. The reversal of 21904722 is 22740912.

21904722 is a `hidden beast` number, since 2 + 190 + 472 + 2 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (21904723) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 62953 + ... + 63299.

It is an arithmetic number, because the mean of its divisors is an integer number (876960).

Almost surely, 2^21904722 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21904722, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28062720).

21904722 is an abundant number, since it is smaller than the sum of its proper divisors (34220718).

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

21904722 is a wasteful number, since it uses less digits than its factorization.

21904722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532 (or 526 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21904722 is about 4680.2480703484. The cubic root of 21904722 is about 279.7988436159.

The spelling of 21904722 in words is "twenty-one million, nine hundred four thousand, seven hundred twenty-two".