21278976 has 72 divisors (see below), whose sum is σ = 57395520. Its totient is φ = 6998016.

The previous prime is 21278963. The next prime is 21278981. The reversal of 21278976 is 67987212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78970 + ... + 79238.

It is an arithmetic number, because the mean of its divisors is an integer number (797160).

Almost surely, 2^21278976 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 21278976, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28697760).

21278976 is an abundant number, since it is smaller than the sum of its proper divisors (36116544).

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

21278976 is a wasteful number, since it uses less digits than its factorization.

21278976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 377 counting only the distinct ones).

The product of its digits is 84672, while the sum is 42.

The square root of 21278976 is about 4612.9140464570. The cubic root of 21278976 is about 277.1087514524.

The spelling of 21278976 in words is "twenty-one million, two hundred seventy-eight thousand, nine hundred seventy-six".