21023212 has 12 divisors (see below), whose sum is σ = 42046480. Its totient is φ = 9009936.

The previous prime is 21023209. The next prime is 21023213. The reversal of 21023212 is 21232012.

21023212 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21023192 and 21023201.

It is not an unprimeable number, because it can be changed into a prime (21023213) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 375387 + ... + 375442.

Almost surely, 2^21023212 is an apocalyptic number.

It is an amenable number.

21023212 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21023212 is a wasteful number, since it uses less digits than its factorization.

21023212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 750840 (or 750838 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21023212 is about 4585.1076323245. The cubic root of 21023212 is about 275.9940312369.

Adding to 21023212 its reverse (21232012), we get a palindrome (42255224).

The spelling of 21023212 in words is "twenty-one million, twenty-three thousand, two hundred twelve".