21145760 has 48 divisors (see below), whose sum is σ = 50240736. Its totient is φ = 8410368.

The previous prime is 21145757. The next prime is 21145769. The reversal of 21145760 is 6754112.

It is not an unprimeable number, because it can be changed into a prime (21145769) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45047 + ... + 45513.

It is an arithmetic number, because the mean of its divisors is an integer number (1046682).

Almost surely, 2^21145760 is an apocalyptic number.

21145760 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 21145760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25120368).

21145760 is an abundant number, since it is smaller than the sum of its proper divisors (29094976).

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

21145760 is a wasteful number, since it uses less digits than its factorization.

21145760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 765 (or 757 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21145760 is about 4598.4519134161. The cubic root of 21145760 is about 276.5292651712.

Adding to 21145760 its reverse (6754112), we get a palindrome (27899872).

The spelling of 21145760 in words is "twenty-one million, one hundred forty-five thousand, seven hundred sixty".