21040110 has 144 divisors (see below), whose sum is σ = 68717376. Its totient is φ = 4427136.

The previous prime is 21040091. The next prime is 21040111. The reversal of 21040110 is 1104012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21040092 and 21040101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040111) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 57147 + ... + 57513.

It is an arithmetic number, because the mean of its divisors is an integer number (477204).

Almost surely, 2^21040110 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21040110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34358688).

21040110 is an abundant number, since it is smaller than the sum of its proper divisors (47677266).

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

21040110 is a wasteful number, since it uses less digits than its factorization.

21040110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21040110 is about 4586.9499670260. The cubic root of 21040110 is about 276.0679574311.

Adding to 21040110 its reverse (1104012), we get a palindrome (22144122).

The spelling of 21040110 in words is "twenty-one million, forty thousand, one hundred ten".