21123212 has 36 divisors (see below), whose sum is σ = 42788760. Its totient is φ = 9092160.

The previous prime is 21123211. The next prime is 21123287. The reversal of 21123212 is 21232112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21123211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8048 + ... + 10344.

Almost surely, 2^21123212 is an apocalyptic number.

21123212 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21123212 is an abundant number, since it is smaller than the sum of its proper divisors (21665548).

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

21123212 is a wasteful number, since it uses less digits than its factorization.

21123212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2342 (or 2329 counting only the distinct ones).

The product of its digits is 48, while the sum is 14.

The square root of 21123212 is about 4595.9995648390. Note that the first 3 decimals coincide. The cubic root of 21123212 is about 276.4309412928.

Adding to 21123212 its reverse (21232112), we get a palindrome (42355324).

Subtracting 21123212 from its reverse (21232112), we obtain a square (108900 = 330²).

The spelling of 21123212 in words is "twenty-one million, one hundred twenty-three thousand, two hundred twelve".