21766680 has 96 divisors (see below), whose sum is σ = 76199760. Its totient is φ = 5356800.

The previous prime is 21766651. The next prime is 21766709. The reversal of 21766680 is 8666712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21766651) and next prime (21766709).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2355 + ... + 7005.

Almost surely, 2^21766680 is an apocalyptic number.

21766680 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 21766680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38099880).

21766680 is an abundant number, since it is smaller than the sum of its proper divisors (54433080).

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

21766680 is a wasteful number, since it uses less digits than its factorization.

21766680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4681 (or 4674 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 21766680 is about 4665.4774675268. The cubic root of 21766680 is about 279.2098471362.

The spelling of 21766680 in words is "twenty-one million, seven hundred sixty-six thousand, six hundred eighty".