21107940 has 96 divisors (see below), whose sum is σ = 69914880. Its totient is φ = 4655616.

The previous prime is 21107929. The next prime is 21107953. The reversal of 21107940 is 4970112.

It is a self number, because there is not a number n which added to its sum of digits gives 21107940.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11314 + ... + 13046.

It is an arithmetic number, because the mean of its divisors is an integer number (728280).

Almost surely, 2^21107940 is an apocalyptic number.

21107940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21107940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34957440).

21107940 is an abundant number, since it is smaller than the sum of its proper divisors (48806940).

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

21107940 is a wasteful number, since it uses less digits than its factorization.

21107940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1781 (or 1779 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21107940 is about 4594.3378195340. The cubic root of 21107940 is about 276.3643057332.

The spelling of 21107940 in words is "twenty-one million, one hundred seven thousand, nine hundred forty".