221769021 has 4 divisors (see below), whose sum is σ = 295692032. Its totient is φ = 147846012.

The previous prime is 221769011. The next prime is 221769047. The reversal of 221769021 is 120967122.

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 not a de Polignac number, because 221769021 - 2⁶ = 221768957 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221769021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221769011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36961501 + ... + 36961506.

It is an arithmetic number, because the mean of its divisors is an integer number (73923008).

Almost surely, 2^221769021 is an apocalyptic number.

It is an amenable number.

221769021 is a deficient number, since it is larger than the sum of its proper divisors (73923011).

221769021 is an equidigital number, since it uses as much as digits as its factorization.

221769021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73923010.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 221769021 is about 14891.9112608154. The cubic root of 221769021 is about 605.2948234074.

The spelling of 221769021 in words is "two hundred twenty-one million, seven hundred sixty-nine thousand, twenty-one".