221721252 has 24 divisors (see below), whose sum is σ = 517851936. Its totient is φ = 73835328.

The previous prime is 221721251. The next prime is 221721257. The reversal of 221721252 is 252127122.

221721252 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (221721251) 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, 4743 + ... + 21585.

It is an arithmetic number, because the mean of its divisors is an integer number (21577164).

Almost surely, 2^221721252 is an apocalyptic number.

It is an amenable number.

221721252 is an abundant number, since it is smaller than the sum of its proper divisors (296130684).

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

221721252 is a wasteful number, since it uses less digits than its factorization.

221721252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17947 (or 17945 counting only the distinct ones).

The product of its digits is 1120, while the sum is 24.

The square root of 221721252 is about 14890.3073171778. The cubic root of 221721252 is about 605.2513601611.

Adding to 221721252 its reverse (252127122), we get a palindrome (473848374).

The spelling of 221721252 in words is "two hundred twenty-one million, seven hundred twenty-one thousand, two hundred fifty-two".