21205122 has 8 divisors (see below), whose sum is σ = 42410256. Its totient is φ = 7068372.

The previous prime is 21205111. The next prime is 21205123. The reversal of 21205122 is 22150212.

It is a sphenic number, since it is the product of 3 distinct primes.

21205122 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21205123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1767088 + ... + 1767099.

It is an arithmetic number, because the mean of its divisors is an integer number (5301282).

Almost surely, 2^21205122 is an apocalyptic number.

21205122 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21205122 is a wasteful number, since it uses less digits than its factorization.

21205122 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3534192.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21205122 is about 4604.9019533536. The cubic root of 21205122 is about 276.7877881305.

Adding to 21205122 its reverse (22150212), we get a palindrome (43355334).

The spelling of 21205122 in words is "twenty-one million, two hundred five thousand, one hundred twenty-two".