21240212 has 12 divisors (see below), whose sum is σ = 42480480. Its totient is φ = 9102936.

The previous prime is 21240211. The next prime is 21240221. The reversal of 21240212 is 21204212.

21240212 is an admirable number.

It is a super-2 number, since 2×21240212² = 902293211609888, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 379262 + ... + 379317.

It is an arithmetic number, because the mean of its divisors is an integer number (3540040).

Almost surely, 2^21240212 is an apocalyptic number.

It is an amenable number.

21240212 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.

21240212 is a wasteful number, since it uses less digits than its factorization.

21240212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758590 (or 758588 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21240212 is about 4608.7104487047. The cubic root of 21240212 is about 276.9403791105.

Adding to 21240212 its reverse (21204212), we get a palindrome (42444424).

The spelling of 21240212 in words is "twenty-one million, two hundred forty thousand, two hundred twelve".