21109550 has 48 divisors (see below), whose sum is σ = 48961152. Its totient is φ = 6578400.

The previous prime is 21109549. The next prime is 21109579. The reversal of 21109550 is 5590112.

It is a super-2 number, since 2×21109550² = 891226202405000, which contains 22 as substring.

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 23 ways as a sum of consecutive naturals, for example, 1109 + ... + 6591.

It is an arithmetic number, because the mean of its divisors is an integer number (1020024).

Almost surely, 2^21109550 is an apocalyptic number.

21109550 is an abundant number, since it is smaller than the sum of its proper divisors (27851602).

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

21109550 is a wasteful number, since it uses less digits than its factorization.

21109550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5513 (or 5508 counting only the distinct ones).

The product of its (nonzero) digits is 450, while the sum is 23.

The square root of 21109550 is about 4594.5130318675. The cubic root of 21109550 is about 276.3713320816.

Adding to 21109550 its reverse (5590112), we get a palindrome (26699662).

The spelling of 21109550 in words is "twenty-one million, one hundred nine thousand, five hundred fifty".