21011244 has 12 divisors (see below), whose sum is σ = 49026264. Its totient is φ = 7003744.

The previous prime is 21011239. The next prime is 21011251. The reversal of 21011244 is 44211012.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 875457 + ... + 875480.

It is an arithmetic number, because the mean of its divisors is an integer number (4085522).

Almost surely, 2^21011244 is an apocalyptic number.

It is an amenable number.

21011244 is an abundant number, since it is smaller than the sum of its proper divisors (28015020).

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

21011244 is a wasteful number, since it uses less digits than its factorization.

21011244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1750944 (or 1750942 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 21011244 is about 4583.8023517599. The cubic root of 21011244 is about 275.9416490802.

Adding to 21011244 its reverse (44211012), we get a palindrome (65222256).

The spelling of 21011244 in words is "twenty-one million, eleven thousand, two hundred forty-four".