21321210 has 32 divisors (see below), whose sum is σ = 51549120. Its totient is φ = 5643648.

The previous prime is 21321203. The next prime is 21321217. The reversal of 21321210 is 1212312.

It is an interprime number because it is at equal distance from previous prime (21321203) and next prime (21321217).

It is not an unprimeable number, because it can be changed into a prime (21321217) 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, 1614 + ... + 6726.

It is an arithmetic number, because the mean of its divisors is an integer number (1610910).

Almost surely, 2^21321210 is an apocalyptic number.

21321210 is an abundant number, since it is smaller than the sum of its proper divisors (30227910).

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

21321210 is a wasteful number, since it uses less digits than its factorization.

21321210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5262.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21321210 is about 4617.4895776818. The cubic root of 21321210 is about 277.2919632237.

Adding to 21321210 its reverse (1212312), we get a palindrome (22533522).

The spelling of 21321210 in words is "twenty-one million, three hundred twenty-one thousand, two hundred ten".