21312210 has 32 divisors (see below), whose sum is σ = 52399872. Its totient is φ = 5544320.

The previous prime is 21312173. The next prime is 21312223. The reversal of 21312210 is 1221312.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7434 + ... + 9893.

It is an arithmetic number, because the mean of its divisors is an integer number (1637496).

Almost surely, 2^21312210 is an apocalyptic number.

21312210 is an abundant number, since it is smaller than the sum of its proper divisors (31087662).

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

21312210 is a wasteful number, since it uses less digits than its factorization.

21312210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17378.

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

The square root of 21312210 is about 4616.5149192871. The cubic root of 21312210 is about 277.2529413780.

Adding to 21312210 its reverse (1221312), we get a palindrome (22533522).

The spelling of 21312210 in words is "twenty-one million, three hundred twelve thousand, two hundred ten".