21143680 has 32 divisors (see below), whose sum is σ = 50548140. Its totient is φ = 8457216.

The previous prime is 21143671. The next prime is 21143719. The reversal of 21143680 is 8634112.

It can be written as a sum of positive squares in 2 ways, for example, as 17239104 + 3904576 = 4152^2 + 1976^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15879 + ... + 17158.

Almost surely, 2^21143680 is an apocalyptic number.

21143680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21143680 is an abundant number, since it is smaller than the sum of its proper divisors (29404460).

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

21143680 is an equidigital number, since it uses as much as digits as its factorization.

21143680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33056 (or 33044 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 21143680 is about 4598.2257447846. The cubic root of 21143680 is about 276.5201979518.

Adding to 21143680 its reverse (8634112), we get a palindrome (29777792).

The spelling of 21143680 in words is "twenty-one million, one hundred forty-three thousand, six hundred eighty".