21206052 has 144 divisors (see below), whose sum is σ = 66626560. Its totient is φ = 5552064.

The previous prime is 21206011. The next prime is 21206117. The reversal of 21206052 is 25060212.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 205833 + ... + 205935.

Almost surely, 2^21206052 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 21206052, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33313280).

21206052 is an abundant number, since it is smaller than the sum of its proper divisors (45420508).

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

21206052 is a wasteful number, since it uses less digits than its factorization.

21206052 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21206052 is about 4605.0029315952. The cubic root of 21206052 is about 276.7918344624.

Adding to 21206052 its reverse (25060212), we get a palindrome (46266264).

The spelling of 21206052 in words is "twenty-one million, two hundred six thousand, fifty-two".