21040244 has 12 divisors (see below), whose sum is σ = 37677024. Its totient is φ = 10275384.

The previous prime is 21040231. The next prime is 21040247. The reversal of 21040244 is 44204012.

21040244 = 55² + 56² + ... + 398².

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040247) 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, 60992 + ... + 61335.

It is an arithmetic number, because the mean of its divisors is an integer number (3139752).

Almost surely, 2^21040244 is an apocalyptic number.

It is an amenable number.

21040244 is a deficient number, since it is larger than the sum of its proper divisors (16636780).

21040244 is a wasteful number, since it uses less digits than its factorization.

21040244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122374 (or 122372 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21040244 is about 4586.9645736587. The cubic root of 21040244 is about 276.0685435026.

Adding to 21040244 its reverse (44204012), we get a palindrome (65244256).

The spelling of 21040244 in words is "twenty-one million, forty thousand, two hundred forty-four".