21109380 has 48 divisors (see below), whose sum is σ = 62220480. Its totient is φ = 5332608.

The previous prime is 21109369. The next prime is 21109381. The reversal of 21109380 is 8390112.

It is a self number, because there is not a number n which added to its sum of digits gives 21109380.

It is not an unprimeable number, because it can be changed into a prime (21109381) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8119 + ... + 10398.

It is an arithmetic number, because the mean of its divisors is an integer number (1296260).

Almost surely, 2^21109380 is an apocalyptic number.

21109380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21109380 is an abundant number, since it is smaller than the sum of its proper divisors (41111100).

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

21109380 is a wasteful number, since it uses less digits than its factorization.

21109380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18548 (or 18546 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21109380 is about 4594.4945315018. The cubic root of 21109380 is about 276.3705901859.

Adding to 21109380 its reverse (8390112), we get a palindrome (29499492).

The spelling of 21109380 in words is "twenty-one million, one hundred nine thousand, three hundred eighty".