21201212 has 24 divisors (see below), whose sum is σ = 37927680.
Its totient is φ = 10367280.
The previous prime is 21201209. The next prime is 21201251. The reversal of 21201212 is 21210212.
Adding to 21201212 its reverse (21210212), we get a palindrome (42411424).
It is a happy number.
It is a junction number, because it is equal to n+sod(n) for n = 21201193 and 21201202.
It is a congruent number.
It is an unprimeable number.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63887 + ... + 64217.
It is an arithmetic number, because the mean of its divisors is an integer number (1580320).
Almost surely, 221201212 is an apocalyptic number.
It is an amenable number.
21201212 is a deficient number, since it is larger than the sum of its proper divisors (16726468).
21201212 is a wasteful number, since it uses less digits than its factorization.
21201212 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 641 (or 639 counting only the distinct ones).
The product of its (nonzero) digits is 16, while the sum is 11.
The square root of 21201212 is about 4604.4773861970.
The cubic root of 21201212 is about 276.7707748389.
The spelling of 21201212 in words is "twenty-one million, two hundred one thousand, two hundred twelve".