21109880 has 32 divisors (see below), whose sum is σ = 51816240. Its totient is φ = 7676160.

The previous prime is 21109877. The next prime is 21109889. The reversal of 21109880 is 8890112.

It is a super-2 number, since 2×21109880² = 891254067228800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21109889) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23549 + ... + 24428.

Almost surely, 2^21109880 is an apocalyptic number.

21109880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21109880 is an abundant number, since it is smaller than the sum of its proper divisors (30706360).

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

21109880 is a wasteful number, since it uses less digits than its factorization.

21109880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47999 (or 47995 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 21109880 is about 4594.5489441293. The cubic root of 21109880 is about 276.3727722207.

Adding to 21109880 its reverse (8890112), we get a palindrome (29999992).

It can be divided in two parts, 21 and 109880, that added together give a palindrome (109901).

The spelling of 21109880 in words is "twenty-one million, one hundred nine thousand, eight hundred eighty".