21251000244 has 24 divisors (see below), whose sum is σ = 50738823520. Its totient is φ = 6918930144.

The previous prime is 21251000231. The next prime is 21251000261. The reversal of 21251000244 is 44200015212.

It is a super-2 number, since 2×21251000244² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21251000244.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20591539 + ... + 20592570.

Almost surely, 2^21251000244 is an apocalyptic number.

It is an amenable number.

21251000244 is an abundant number, since it is smaller than the sum of its proper divisors (29487823276).

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

21251000244 is a wasteful number, since it uses less digits than its factorization.

21251000244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41184159 (or 41184157 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 21.

Adding to 21251000244 its reverse (44200015212), we get a palindrome (65451015456).

The spelling of 21251000244 in words is "twenty-one billion, two hundred fifty-one million, two hundred forty-four", and thus it is an aban number.