21416640 has 112 divisors (see below), whose sum is σ = 77736192. Its totient is φ = 4893696.

The previous prime is 21416609. The next prime is 21416641. The reversal of 21416640 is 4661412.

It is a tau number, because it is divible by the number of its divisors (112).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21416640.

It is not an unprimeable number, because it can be changed into a prime (21416641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5127 + ... + 8313.

Almost surely, 2^21416640 is an apocalyptic number.

21416640 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 21416640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38868096).

21416640 is an abundant number, since it is smaller than the sum of its proper divisors (56319552).

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

21416640 is a wasteful number, since it uses less digits than its factorization.

21416640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3214 (or 3204 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21416640 is about 4627.8115778411. The cubic root of 21416640 is about 277.7050509458.

The spelling of 21416640 in words is "twenty-one million, four hundred sixteen thousand, six hundred forty".