21278322 has 64 divisors (see below), whose sum is σ = 53948160. Its totient is φ = 6158592.

The previous prime is 21278317. The next prime is 21278363. The reversal of 21278322 is 22387212.

It is a happy number.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11043 + ... + 12825.

It is an arithmetic number, because the mean of its divisors is an integer number (842940).

Almost surely, 2^21278322 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21278322, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26974080).

21278322 is an abundant number, since it is smaller than the sum of its proper divisors (32669838).

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

21278322 is a wasteful number, since it uses less digits than its factorization.

21278322 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1824 (or 1818 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 21278322 is about 4612.8431579667. The cubic root of 21278322 is about 277.1059124847.

The spelling of 21278322 in words is "twenty-one million, two hundred seventy-eight thousand, three hundred twenty-two".