21366558 has 16 divisors (see below), whose sum is σ = 47481360. Its totient is φ = 7122168.

The previous prime is 21366557. The next prime is 21366581. The reversal of 21366558 is 85566312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366551) 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 7 ways as a sum of consecutive naturals, for example, 197785 + ... + 197892.

It is an arithmetic number, because the mean of its divisors is an integer number (2967585).

Almost surely, 2^21366558 is an apocalyptic number.

21366558 is an abundant number, since it is smaller than the sum of its proper divisors (26114802).

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

21366558 is a wasteful number, since it uses less digits than its factorization.

21366558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395688 (or 395682 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 21366558 is about 4622.3974299058. The cubic root of 21366558 is about 277.4884144177.

The spelling of 21366558 in words is "twenty-one million, three hundred sixty-six thousand, five hundred fifty-eight".