21679680 has 112 divisors (see below), whose sum is σ = 75127104. Its totient is φ = 5253120.

The previous prime is 21679673. The next prime is 21679681. The reversal of 21679680 is 8697612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21679681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9534 + ... + 11586.

Almost surely, 2^21679680 is an apocalyptic number.

21679680 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 21679680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37563552).

21679680 is an abundant number, since it is smaller than the sum of its proper divisors (53447424).

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

21679680 is a wasteful number, since it uses less digits than its factorization.

21679680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2084 (or 2074 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21679680 is about 4656.1443276600. The cubic root of 21679680 is about 278.8373559052.

The spelling of 21679680 in words is "twenty-one million, six hundred seventy-nine thousand, six hundred eighty".