21243210 has 32 divisors (see below), whose sum is σ = 51131520. Its totient is φ = 5648448.

The previous prime is 21243193. The next prime is 21243227. The reversal of 21243210 is 1234212.

It is an interprime number because it is at equal distance from previous prime (21243193) and next prime (21243227).

It is a super-2 number, since 2×21243210² = 902547942208200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21243210.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12364 + ... + 13976.

It is an arithmetic number, because the mean of its divisors is an integer number (1597860).

Almost surely, 2^21243210 is an apocalyptic number.

21243210 is an abundant number, since it is smaller than the sum of its proper divisors (29888310).

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

21243210 is a wasteful number, since it uses less digits than its factorization.

21243210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2062.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21243210 is about 4609.0356909011. The cubic root of 21243210 is about 276.9534082992.

Adding to 21243210 its reverse (1234212), we get a palindrome (22477422).

The spelling of 21243210 in words is "twenty-one million, two hundred forty-three thousand, two hundred ten".