21818480 has 80 divisors (see below), whose sum is σ = 54800064. Its totient is φ = 8048640.

The previous prime is 21818471. The next prime is 21818491. The reversal of 21818480 is 8481812.

It is a tau number, because it is divible by the number of its divisors (80).

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, 82829 + ... + 83091.

Almost surely, 2^21818480 is an apocalyptic number.

21818480 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 21818480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27400032).

21818480 is an abundant number, since it is smaller than the sum of its proper divisors (32981584).

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

21818480 is a wasteful number, since it uses less digits than its factorization.

21818480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354 (or 348 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 21818480 is about 4671.0255833168. The cubic root of 21818480 is about 279.4311580608.

The spelling of 21818480 in words is "twenty-one million, eight hundred eighteen thousand, four hundred eighty".