21478284 has 72 divisors (see below), whose sum is σ = 59317440. Its totient is φ = 6776784.

The previous prime is 21478277. The next prime is 21478291. The reversal of 21478284 is 48287412.

It is an interprime number because it is at equal distance from previous prime (21478277) and next prime (21478291).

It is a super-2 number, since 2×21478284² = 922633367169312, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17887 + ... + 19049.

Almost surely, 2^21478284 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 21478284, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29658720).

21478284 is an abundant number, since it is smaller than the sum of its proper divisors (37839156).

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

21478284 is a wasteful number, since it uses less digits than its factorization.

21478284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1201 (or 1187 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 21478284 is about 4634.4669596406. The cubic root of 21478284 is about 277.9712372982.

The spelling of 21478284 in words is "twenty-one million, four hundred seventy-eight thousand, two hundred eighty-four".