21487680 has 140 divisors (see below), whose sum is σ = 76527660. Its totient is φ = 5723136.

The previous prime is 21487673. The next prime is 21487693. The reversal of 21487680 is 8678412.

It can be written as a sum of positive squares in 2 ways, for example, as 10036224 + 11451456 = 3168^2 + 3384^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 25506 + ... + 26334.

It is a vampire number, since it can be written as 2880 ⋅ 7461 (with its own digits).

Almost surely, 2^21487680 is an apocalyptic number.

21487680 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 21487680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38263830).

21487680 is an abundant number, since it is smaller than the sum of its proper divisors (55039980).

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

21487680 is an equidigital number, since it uses as much as digits as its factorization.

21487680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 858 (or 839 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 21487680 is about 4635.4805576121. The cubic root of 21487680 is about 278.0117656287.

The spelling of 21487680 in words is "twenty-one million, four hundred eighty-seven thousand, six hundred eighty".