21786680 has 16 divisors (see below), whose sum is σ = 49020120. Its totient is φ = 8714656.

The previous prime is 21786679. The next prime is 21786683. The reversal of 21786680 is 8668712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21786683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 272294 + ... + 272373.

Almost surely, 2^21786680 is an apocalyptic number.

21786680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21786680 is an abundant number, since it is smaller than the sum of its proper divisors (27233440).

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

21786680 is a wasteful number, since it uses less digits than its factorization.

21786680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544678 (or 544674 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 21786680 is about 4667.6203787369. The cubic root of 21786680 is about 279.2953369382.

The spelling of 21786680 in words is "twenty-one million, seven hundred eighty-six thousand, six hundred eighty".