21369208 has 64 divisors (see below), whose sum is σ = 48936960. Its totient is φ = 8549376.

The previous prime is 21369109. The next prime is 21369209. The reversal of 21369208 is 80296312.

It is a super-4 number, since 4×21369208⁴ (a number of 30 digits) contains 4444 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21369208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21369209) 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, 60360 + ... + 60712.

It is an arithmetic number, because the mean of its divisors is an integer number (764640).

Almost surely, 2^21369208 is an apocalyptic number.

21369208 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 21369208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24468480).

21369208 is an abundant number, since it is smaller than the sum of its proper divisors (27567752).

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

21369208 is a wasteful number, since it uses less digits than its factorization.

21369208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436 (or 432 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21369208 is about 4622.6840688068. The cubic root of 21369208 is about 277.4998858317.

The spelling of 21369208 in words is "twenty-one million, three hundred sixty-nine thousand, two hundred eight".