21001112 has 16 divisors (see below), whose sum is σ = 42957000. Its totient is φ = 9545920.

The previous prime is 21001087. The next prime is 21001117. The reversal of 21001112 is 21110012.

It is a Harshad number since it is a multiple of its sum of digits (8).

It is a self number, because there is not a number n which added to its sum of digits gives 21001112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119237 + ... + 119412.

Almost surely, 2^21001112 is an apocalyptic number.

21001112 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21001112 is an abundant number, since it is smaller than the sum of its proper divisors (21955888).

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

21001112 is a wasteful number, since it uses less digits than its factorization.

21001112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238666 (or 238662 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

The square root of 21001112 is about 4582.6970224967. The cubic root of 21001112 is about 275.8972872723.

Adding to 21001112 its reverse (21110012), we get a palindrome (42111124).

Subtracting 21001112 from its reverse (21110012), we obtain a square (108900 = 330²).

The spelling of 21001112 in words is "twenty-one million, one thousand, one hundred twelve".