21336687 has 24 divisors (see below), whose sum is σ = 32196528. Its totient is φ = 13603200.

The previous prime is 21336671. The next prime is 21336697. The reversal of 21336687 is 78663312.

It is a happy number.

21336687 is a `hidden beast` number, since 213 + 366 + 87 = 666.

It is not a de Polignac number, because 21336687 - 2⁴ = 21336671 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21336647) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 19012 + ... + 20102.

It is an arithmetic number, because the mean of its divisors is an integer number (1341522).

Almost surely, 2^21336687 is an apocalyptic number.

21336687 is a deficient number, since it is larger than the sum of its proper divisors (10859841).

21336687 is a wasteful number, since it uses less digits than its factorization.

21336687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1191 (or 1188 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 21336687 is about 4619.1651843163. The cubic root of 21336687 is about 277.3590421200.

Adding to 21336687 its reverse (78663312), we get a palindrome (99999999).

The spelling of 21336687 in words is "twenty-one million, three hundred thirty-six thousand, six hundred eighty-seven".