21128968 has 32 divisors (see below), whose sum is σ = 45460800. Its totient is φ = 9018432.

The previous prime is 21128959. The next prime is 21128971. The reversal of 21128968 is 86982112.

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16578 + ... + 17806.

It is an arithmetic number, because the mean of its divisors is an integer number (1420650).

Almost surely, 2^21128968 is an apocalyptic number.

21128968 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21128968 is an abundant number, since it is smaller than the sum of its proper divisors (24331832).

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

21128968 is a wasteful number, since it uses less digits than its factorization.

21128968 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1549 (or 1545 counting only the distinct ones).

The product of its digits is 13824, while the sum is 37.

The square root of 21128968 is about 4596.6257189378. The cubic root of 21128968 is about 276.4560478279.

The spelling of 21128968 in words is "twenty-one million, one hundred twenty-eight thousand, nine hundred sixty-eight".