21417280 has 112 divisors (see below), whose sum is σ = 56180736. Its totient is φ = 7741440.

The previous prime is 21417271. The next prime is 21417299. The reversal of 21417280 is 8271412.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 168577 + ... + 168703.

Almost surely, 2^21417280 is an apocalyptic number.

21417280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21417280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28090368).

21417280 is an abundant number, since it is smaller than the sum of its proper divisors (34763456).

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

21417280 is a wasteful number, since it uses less digits than its factorization.

21417280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192 (or 182 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21417280 is about 4627.8807244785. The cubic root of 21417280 is about 277.7078171665.

Adding to 21417280 its reverse (8271412), we get a palindrome (29688692).

The spelling of 21417280 in words is "twenty-one million, four hundred seventeen thousand, two hundred eighty".