21212152 has 32 divisors (see below), whose sum is σ = 43570800. Its totient is φ = 9621504.

The previous prime is 21212143. The next prime is 21212159. The reversal of 21212152 is 25121212.

It is a happy number.

It is a super-2 number, since 2×21212152² = 899910784942208, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212159) 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, 4408 + ... + 7864.

Almost surely, 2^21212152 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21785400).

21212152 is an abundant number, since it is smaller than the sum of its proper divisors (22358648).

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

21212152 is a wasteful number, since it uses less digits than its factorization.

21212152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3535 (or 3531 counting only the distinct ones).

The product of its digits is 80, while the sum is 16.

The square root of 21212152 is about 4605.6652071118. The cubic root of 21212152 is about 276.8183719860.

Adding to 21212152 its reverse (25121212), we get a palindrome (46333364).

The spelling of 21212152 in words is "twenty-one million, two hundred twelve thousand, one hundred fifty-two".