21303408 has 160 divisors (see below), whose sum is σ = 68567040. Its totient is φ = 5564160.

The previous prime is 21303407. The next prime is 21303409. The reversal of 21303408 is 80430312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21303407) and next prime (21303409).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303407) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 300013 + ... + 300083.

It is an arithmetic number, because the mean of its divisors is an integer number (428544).

Almost surely, 2^21303408 is an apocalyptic number.

21303408 is a gapful number since it is divisible by the number (28) 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 21303408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34283520).

21303408 is an abundant number, since it is smaller than the sum of its proper divisors (47263632).

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

21303408 is a wasteful number, since it uses less digits than its factorization.

21303408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21303408 is about 4615.5615043026. The cubic root of 21303408 is about 277.2147673856.

The spelling of 21303408 in words is "twenty-one million, three hundred three thousand, four hundred eight".