21307260 has 96 divisors (see below), whose sum is σ = 65479680. Its totient is φ = 5144832.

The previous prime is 21307243. The next prime is 21307271. The reversal of 21307260 is 6270312.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45789 + ... + 46251.

It is an arithmetic number, because the mean of its divisors is an integer number (682080).

Almost surely, 2^21307260 is an apocalyptic number.

21307260 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 21307260, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32739840).

21307260 is an abundant number, since it is smaller than the sum of its proper divisors (44172420).

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

21307260 is a wasteful number, since it uses less digits than its factorization.

21307260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547 (or 545 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21307260 is about 4615.9787694486. The cubic root of 21307260 is about 277.2314746801.

Adding to 21307260 its reverse (6270312), we get a palindrome (27577572).

The spelling of 21307260 in words is "twenty-one million, three hundred seven thousand, two hundred sixty".