221709245 has 4 divisors (see below), whose sum is σ = 266051100. Its totient is φ = 177367392.

The previous prime is 221709239. The next prime is 221709287. The reversal of 221709245 is 542907122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29997529 + 191711716 = 5477^2 + 13846^2 .

It is a cyclic number.

It is not a de Polignac number, because 221709245 - 2¹⁸ = 221447101 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22170920 + ... + 22170929.

It is an arithmetic number, because the mean of its divisors is an integer number (66512775).

Almost surely, 2^221709245 is an apocalyptic number.

It is an amenable number.

221709245 is a deficient number, since it is larger than the sum of its proper divisors (44341855).

221709245 is an equidigital number, since it uses as much as digits as its factorization.

221709245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44341854.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 221709245 is about 14889.9041299802. The cubic root of 221709245 is about 605.2404344542.

The spelling of 221709245 in words is "two hundred twenty-one million, seven hundred nine thousand, two hundred forty-five".