21205002 has 64 divisors (see below), whose sum is σ = 53028864. Its totient is φ = 5503680.

The previous prime is 21204949. The next prime is 21205021. The reversal of 21205002 is 20050212.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 38493 + ... + 39039.

It is an arithmetic number, because the mean of its divisors is an integer number (828576).

Almost surely, 2^21205002 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21205002, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26514432).

21205002 is an abundant number, since it is smaller than the sum of its proper divisors (31823862).

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

21205002 is a wasteful number, since it uses less digits than its factorization.

21205002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643.

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 21205002 is about 4604.8889237418. Note that the first 3 decimals coincide. The cubic root of 21205002 is about 276.7872660146.

Adding to 21205002 its reverse (20050212), we get a palindrome (41255214).

The spelling of 21205002 in words is "twenty-one million, two hundred five thousand, two".