21856422 has 64 divisors (see below), whose sum is σ = 53568000. Its totient is φ = 5806080.

The previous prime is 21856409. The next prime is 21856423. The reversal of 21856422 is 22465812.

It is a self number, because there is not a number n which added to its sum of digits gives 21856422.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21856423) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 48454 + ... + 48902.

It is an arithmetic number, because the mean of its divisors is an integer number (837000).

Almost surely, 2^21856422 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21856422, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26784000).

21856422 is an abundant number, since it is smaller than the sum of its proper divisors (31711578).

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

21856422 is a wasteful number, since it uses less digits than its factorization.

21856422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541.

The product of its digits is 7680, while the sum is 30.

The square root of 21856422 is about 4675.0852398646. The cubic root of 21856422 is about 279.5930397509.

The spelling of 21856422 in words is "twenty-one million, eight hundred fifty-six thousand, four hundred twenty-two".