21336020 has 24 divisors (see below), whose sum is σ = 47442024. Its totient is φ = 8032256.

The previous prime is 21336017. The next prime is 21336047. The reversal of 21336020 is 2063312.

It can be written as a sum of positive squares in 4 ways, for example, as 4656964 + 16679056 = 2158^2 + 4084^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a self number, because there is not a number n which added to its sum of digits gives 21336020.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31037 + ... + 31716.

It is an arithmetic number, because the mean of its divisors is an integer number (1976751).

Almost surely, 2^21336020 is an apocalyptic number.

21336020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21336020 is an abundant number, since it is smaller than the sum of its proper divisors (26106004).

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

21336020 is a wasteful number, since it uses less digits than its factorization.

21336020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62779 (or 62777 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21336020 is about 4619.0929845588. The cubic root of 21336020 is about 277.3561519429.

Adding to 21336020 its reverse (2063312), we get a palindrome (23399332).

The spelling of 21336020 in words is "twenty-one million, three hundred thirty-six thousand, twenty".