21818916 has 192 divisors, whose sum is σ = 71680000. Its totient is φ = 5715360.

The previous prime is 21818899. The next prime is 21818921. The reversal of 21818916 is 61981812.

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 63 ways as a sum of consecutive naturals, for example, 703821 + ... + 703851.

Almost surely, 2^21818916 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 21818916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35840000).

21818916 is an abundant number, since it is smaller than the sum of its proper divisors (49861084).

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

21818916 is a wasteful number, since it uses less digits than its factorization.

21818916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 62 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 21818916 is about 4671.0722537764. The cubic root of 21818916 is about 279.4330193450.

The spelling of 21818916 in words is "twenty-one million, eight hundred eighteen thousand, nine hundred sixteen".