21286680 has 64 divisors (see below), whose sum is σ = 64281600. Its totient is φ = 5639040.

The previous prime is 21286673. The next prime is 21286691. The reversal of 21286680 is 8668212.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 20985 + ... + 21975.

It is an arithmetic number, because the mean of its divisors is an integer number (1004400).

Almost surely, 2^21286680 is an apocalyptic number.

21286680 is a gapful number since it is divisible by the number (20) 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 21286680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32140800).

21286680 is an abundant number, since it is smaller than the sum of its proper divisors (42994920).

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

21286680 is a wasteful number, since it uses less digits than its factorization.

21286680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1184 (or 1180 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 21286680 is about 4613.7490178812. The cubic root of 21286680 is about 277.1421895940.

The spelling of 21286680 in words is "twenty-one million, two hundred eighty-six thousand, six hundred eighty".