21313380 has 96 divisors (see below), whose sum is σ = 66705408. Its totient is φ = 5040000.

The previous prime is 21313379. The next prime is 21313429. The reversal of 21313380 is 8331312.

It is a happy 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, 28005 + ... + 28755.

It is an arithmetic number, because the mean of its divisors is an integer number (694848).

Almost surely, 2^21313380 is an apocalyptic number.

21313380 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 21313380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33352704).

21313380 is an abundant number, since it is smaller than the sum of its proper divisors (45392028).

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

21313380 is a wasteful number, since it uses less digits than its factorization.

21313380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817 (or 815 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21313380 is about 4616.6416365146. The cubic root of 21313380 is about 277.2580148391.

Adding to 21313380 its reverse (8331312), we get a palindrome (29644692).

The spelling of 21313380 in words is "twenty-one million, three hundred thirteen thousand, three hundred eighty".