21231210 has 192 divisors, whose sum is σ = 70326144. Its totient is φ = 4032000.

The previous prime is 21231173. The next prime is 21231241. The reversal of 21231210 is 1213212.

21231210 = T₃₆₄ + T₃₆₅ + ... + T₅₅₉.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 210160 + ... + 210260.

It is an arithmetic number, because the mean of its divisors is an integer number (366282).

Almost surely, 2^21231210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21231210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35163072).

21231210 is an abundant number, since it is smaller than the sum of its proper divisors (49094934).

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

21231210 is a wasteful number, since it uses less digits than its factorization.

21231210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149 (or 142 counting only the distinct ones).

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

The square root of 21231210 is about 4607.7337162644. The cubic root of 21231210 is about 276.9012494073.

Adding to 21231210 its reverse (1213212), we get a palindrome (22444422).

It can be divided in two parts, 2123 and 1210, that added together give a palindrome (3333).

The spelling of 21231210 in words is "twenty-one million, two hundred thirty-one thousand, two hundred ten".