21001120 has 96 divisors (see below), whose sum is σ = 60092928. Its totient is φ = 6770688.

The previous prime is 21001117. The next prime is 21001121. The reversal of 21001120 is 2110012.

It is a Harshad number since it is a multiple of its sum of digits (7).

It is not an unprimeable number, because it can be changed into a prime (21001121) 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, 18489 + ... + 19591.

It is an arithmetic number, because the mean of its divisors is an integer number (625968).

Almost surely, 2^21001120 is an apocalyptic number.

21001120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21001120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30046464).

21001120 is an abundant number, since it is smaller than the sum of its proper divisors (39091808).

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

21001120 is a wasteful number, since it uses less digits than its factorization.

21001120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1142 (or 1134 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21001120 is about 4582.6978953451. The cubic root of 21001120 is about 275.8973223050.

Adding to 21001120 its reverse (2110012), we get a palindrome (23111132).

The spelling of 21001120 in words is "twenty-one million, one thousand, one hundred twenty".