21338416 has 40 divisors (see below), whose sum is σ = 46568448. Its totient is φ = 9384000.

The previous prime is 21338357. The next prime is 21338431. The reversal of 21338416 is 61483312.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3501 + ... + 7411.

Almost surely, 2^21338416 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 21338416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23284224).

21338416 is an abundant number, since it is smaller than the sum of its proper divisors (25230032).

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

21338416 is a wasteful number, since it uses less digits than its factorization.

21338416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3961 (or 3955 counting only the distinct ones).

The product of its digits is 3456, while the sum is 28.

The square root of 21338416 is about 4619.3523355553. The cubic root of 21338416 is about 277.3665337678.

Subtracting 21338416 from its reverse (61483312), we obtain a square (40144896 = 6336²).

The spelling of 21338416 in words is "twenty-one million, three hundred thirty-eight thousand, four hundred sixteen".