21144760 has 128 divisors (see below), whose sum is σ = 60520320. Its totient is φ = 6469632.

The previous prime is 21144743. The next prime is 21144763. The reversal of 21144760 is 6744112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144763) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 134602 + ... + 134758.

It is an arithmetic number, because the mean of its divisors is an integer number (472815).

Almost surely, 2^21144760 is an apocalyptic number.

21144760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21144760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30260160).

21144760 is an abundant number, since it is smaller than the sum of its proper divisors (39375560).

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

21144760 is a wasteful number, since it uses less digits than its factorization.

21144760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225 (or 221 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21144760 is about 4598.3431798856. The cubic root of 21144760 is about 276.5249060053.

Adding to 21144760 its reverse (6744112), we get a palindrome (27888872).

It can be divided in two parts, 21144 and 760, that added together give a square (21904 = 148²).

The spelling of 21144760 in words is "twenty-one million, one hundred forty-four thousand, seven hundred sixty".