21203408 has 20 divisors (see below), whose sum is σ = 42499140. Its totient is φ = 10235904.

The previous prime is 21203407. The next prime is 21203419. The reversal of 21203408 is 80430212.

It can be written as a sum of positive squares in 2 ways, for example, as 9314704 + 11888704 = 3052^2 + 3448^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21203408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22385 + ... + 23312.

It is an arithmetic number, because the mean of its divisors is an integer number (2124957).

Almost surely, 2^21203408 is an apocalyptic number.

It is an amenable number.

21203408 is an abundant number, since it is smaller than the sum of its proper divisors (21295732).

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

21203408 is a wasteful number, since it uses less digits than its factorization.

21203408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45734 (or 45728 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21203408 is about 4604.7158435673. The cubic root of 21203408 is about 276.7803303875.

The spelling of 21203408 in words is "twenty-one million, two hundred three thousand, four hundred eight".