21235680 has 72 divisors (see below), whose sum is σ = 72471672. Its totient is φ = 5662464.

The previous prime is 21235657. The next prime is 21235723. The reversal of 21235680 is 8653212.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5934 + ... + 8813.

It is an arithmetic number, because the mean of its divisors is an integer number (1006551).

Almost surely, 2^21235680 is an apocalyptic number.

21235680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21235680 is an abundant number, since it is smaller than the sum of its proper divisors (51235992).

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

21235680 is a wasteful number, since it uses less digits than its factorization.

21235680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14768 (or 14757 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 21235680 is about 4608.2187448080. The cubic root of 21235680 is about 276.9206808909.

Adding to 21235680 its reverse (8653212), we get a palindrome (29888892).

The spelling of 21235680 in words is "twenty-one million, two hundred thirty-five thousand, six hundred eighty".