21388338 has 24 divisors (see below), whose sum is σ = 48781200. Its totient is φ = 6754104.

The previous prime is 21388333. The next prime is 21388373. The reversal of 21388338 is 83388312.

21388338 = 877² + 878² + ... + 903².

It is a super-2 number, since 2×21388338² = 914922004804488, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21388333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30928 + ... + 31611.

It is an arithmetic number, because the mean of its divisors is an integer number (2032550).

Almost surely, 2^21388338 is an apocalyptic number.

21388338 is an abundant number, since it is smaller than the sum of its proper divisors (27392862).

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

21388338 is a wasteful number, since it uses less digits than its factorization.

21388338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62566 (or 62563 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 21388338 is about 4624.7527501478. The cubic root of 21388338 is about 277.5826683336.

The spelling of 21388338 in words is "twenty-one million, three hundred eighty-eight thousand, three hundred thirty-eight".