21011144 has 64 divisors (see below), whose sum is σ = 51287040. Its totient is φ = 7824960.

The previous prime is 21011143. The next prime is 21011173. The reversal of 21011144 is 44111012.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is not an unprimeable number, because it can be changed into a prime (21011141) 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, 13427 + ... + 14909.

It is an arithmetic number, because the mean of its divisors is an integer number (801360).

Almost surely, 2^21011144 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 21011144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25643520).

21011144 is an abundant number, since it is smaller than the sum of its proper divisors (30275896).

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

21011144 is a wasteful number, since it uses less digits than its factorization.

21011144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1530 (or 1526 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 21011144 is about 4583.7914437723. The cubic root of 21011144 is about 275.9412113113.

Adding to 21011144 its reverse (44111012), we get a palindrome (65122156).

The spelling of 21011144 in words is "twenty-one million, eleven thousand, one hundred forty-four".