21125680 has 20 divisors (see below), whose sum is σ = 49117392. Its totient is φ = 8450240.

The previous prime is 21125669. The next prime is 21125683. The reversal of 21125680 is 8652112.

It is a tau number, because it is divible by the number of its divisors (20).

It is not an unprimeable number, because it can be changed into a prime (21125683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131956 + ... + 132115.

Almost surely, 2^21125680 is an apocalyptic number.

21125680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21125680 is an abundant number, since it is smaller than the sum of its proper divisors (27991712).

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

21125680 is a wasteful number, since it uses less digits than its factorization.

21125680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264084 (or 264078 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 21125680 is about 4596.2680513652. The cubic root of 21125680 is about 276.4417067798.

Adding to 21125680 its reverse (8652112), we get a palindrome (29777792).

The spelling of 21125680 in words is "twenty-one million, one hundred twenty-five thousand, six hundred eighty".