21318330 has 32 divisors (see below), whose sum is σ = 55816128. Its totient is φ = 5168000.

The previous prime is 21318317. The next prime is 21318337. The reversal of 21318330 is 3381312.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21318297 and 21318306.

It is not an unprimeable number, because it can be changed into a prime (21318337) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31971 + ... + 32630.

It is an arithmetic number, because the mean of its divisors is an integer number (1744254).

Almost surely, 2^21318330 is an apocalyptic number.

21318330 is an abundant number, since it is smaller than the sum of its proper divisors (34497798).

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

21318330 is a wasteful number, since it uses less digits than its factorization.

21318330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64622.

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

The square root of 21318330 is about 4617.1777093805. The cubic root of 21318330 is about 277.2794774280.

Adding to 21318330 its reverse (3381312), we get a palindrome (24699642).

The spelling of 21318330 in words is "twenty-one million, three hundred eighteen thousand, three hundred thirty".