21013212 has 24 divisors (see below), whose sum is σ = 53488512. Its totient is φ = 6367600.

The previous prime is 21013189. The next prime is 21013217. The reversal of 21013212 is 21231012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013217) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79464 + ... + 79727.

It is an arithmetic number, because the mean of its divisors is an integer number (2228688).

Almost surely, 2^21013212 is an apocalyptic number.

21013212 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21013212 is an abundant number, since it is smaller than the sum of its proper divisors (32475300).

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

21013212 is a wasteful number, since it uses less digits than its factorization.

21013212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159209 (or 159207 counting only the distinct ones).

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

The square root of 21013212 is about 4584.0170156752. The cubic root of 21013212 is about 275.9502640899.

Adding to 21013212 its reverse (21231012), we get a palindrome (42244224).

The spelling of 21013212 in words is "twenty-one million, thirteen thousand, two hundred twelve".