21251140 has 12 divisors (see below), whose sum is σ = 44627436. Its totient is φ = 8500448.

The previous prime is 21251137. The next prime is 21251141. The reversal of 21251140 is 4115212.

It can be written as a sum of positive squares in 2 ways, for example, as 10188864 + 11062276 = 3192^2 + 3326^2 .

It is a super-2 number, since 2×21251140² = 903221902599200, which contains 22 as substring.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21251141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 531259 + ... + 531298.

It is an arithmetic number, because the mean of its divisors is an integer number (3718953).

Almost surely, 2^21251140 is an apocalyptic number.

21251140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21251140 is an abundant number, since it is smaller than the sum of its proper divisors (23376296).

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

21251140 is a wasteful number, since it uses less digits than its factorization.

21251140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1062566 (or 1062564 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21251140 is about 4609.8958773491. The cubic root of 21251140 is about 276.9878658554.

Adding to 21251140 its reverse (4115212), we get a palindrome (25366352).

The spelling of 21251140 in words is "twenty-one million, two hundred fifty-one thousand, one hundred forty".