21278496 has 72 divisors (see below), whose sum is σ = 58529520. Its totient is φ = 6768256.

The previous prime is 21278483. The next prime is 21278497. The reversal of 21278496 is 69487212.

It is not an unprimeable number, because it can be changed into a prime (21278497) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50575 + ... + 50993.

It is an arithmetic number, because the mean of its divisors is an integer number (812910).

Almost surely, 2^21278496 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 21278496, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29264760).

21278496 is an abundant number, since it is smaller than the sum of its proper divisors (37251024).

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

21278496 is a wasteful number, since it uses less digits than its factorization.

21278496 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478 (or 447 counting only the distinct ones).

The product of its digits is 48384, while the sum is 39.

The square root of 21278496 is about 4612.8620183136. The cubic root of 21278496 is about 277.1066678120.

The spelling of 21278496 in words is "twenty-one million, two hundred seventy-eight thousand, four hundred ninety-six".