21209202 has 80 divisors (see below), whose sum is σ = 55408320. Its totient is φ = 5938272.

The previous prime is 21209189. The next prime is 21209207. The reversal of 21209202 is 20290212.

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

It is not an unprimeable number, because it can be changed into a prime (21209207) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 66748 + ... + 67064.

It is an arithmetic number, because the mean of its divisors is an integer number (692604).

Almost surely, 2^21209202 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21209202, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27704160).

21209202 is an abundant number, since it is smaller than the sum of its proper divisors (34199118).

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

21209202 is a wasteful number, since it uses less digits than its factorization.

21209202 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 21209202 is about 4605.3449382212. The cubic root of 21209202 is about 276.8055389009.

Adding to 21209202 its reverse (20290212), we get a palindrome (41499414).

The spelling of 21209202 in words is "twenty-one million, two hundred nine thousand, two hundred two".