21278214 has 80 divisors (see below), whose sum is σ = 52039680. Its totient is φ = 6473520.

The previous prime is 21278189. The next prime is 21278261. The reversal of 21278214 is 41287212.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 95307 + ... + 95529.

It is an arithmetic number, because the mean of its divisors is an integer number (650496).

Almost surely, 2^21278214 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21278214, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26019840).

21278214 is an abundant number, since it is smaller than the sum of its proper divisors (30761466).

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

21278214 is a wasteful number, since it uses less digits than its factorization.

21278214 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287 (or 278 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 21278214 is about 4612.8314515057. The cubic root of 21278214 is about 277.1054436587.

The spelling of 21278214 in words is "twenty-one million, two hundred seventy-eight thousand, two hundred fourteen".