21110436 has 48 divisors (see below), whose sum is σ = 55675200. Its totient is φ = 6915456.

The previous prime is 21110431. The next prime is 21110437. The reversal of 21110436 is 63401112.

It is a happy number.

It is a super-2 number, since 2×21110436² = 891301016220192, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21110431) 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, 4716 + ... + 8028.

It is an arithmetic number, because the mean of its divisors is an integer number (1159900).

Almost surely, 2^21110436 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21110436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27837600).

21110436 is an abundant number, since it is smaller than the sum of its proper divisors (34564764).

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

21110436 is a wasteful number, since it uses less digits than its factorization.

21110436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3385 (or 3377 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 21110436 is about 4594.6094502145. The cubic root of 21110436 is about 276.3751986029.

Adding to 21110436 its reverse (63401112), we get a palindrome (84511548).

The spelling of 21110436 in words is "twenty-one million, one hundred ten thousand, four hundred thirty-six".