21210680 has 16 divisors (see below), whose sum is σ = 47724120. Its totient is φ = 8484256.

The previous prime is 21210649. The next prime is 21210691. The reversal of 21210680 is 8601212.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265094 + ... + 265173.

Almost surely, 2^21210680 is an apocalyptic number.

21210680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210680 is an abundant number, since it is smaller than the sum of its proper divisors (26513440).

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

21210680 is a wasteful number, since it uses less digits than its factorization.

21210680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530278 (or 530274 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21210680 is about 4605.5054011476. The cubic root of 21210680 is about 276.8119686428.

Adding to 21210680 its reverse (8601212), we get a palindrome (29811892).

The spelling of 21210680 in words is "twenty-one million, two hundred ten thousand, six hundred eighty".