221522021 has 4 divisors (see below), whose sum is σ = 253168032. Its totient is φ = 189876012.

The previous prime is 221522011. The next prime is 221522023. The reversal of 221522021 is 120225122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221522021 - 2¹⁴ = 221505637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221522023) 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, 15822995 + ... + 15823008.

It is an arithmetic number, because the mean of its divisors is an integer number (63292008).

Almost surely, 2^221522021 is an apocalyptic number.

It is an amenable number.

221522021 is a deficient number, since it is larger than the sum of its proper divisors (31646011).

221522021 is an equidigital number, since it uses as much as digits as its factorization.

221522021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31646010.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 221522021 is about 14883.6158577141. The cubic root of 221522021 is about 605.0700198995.

Adding to 221522021 its reverse (120225122), we get a palindrome (341747143).

The spelling of 221522021 in words is "two hundred twenty-one million, five hundred twenty-two thousand, twenty-one".