221609601 has 10 divisors (see below), whose sum is σ = 331046562. Its totient is φ = 147739680.

The previous prime is 221609599. The next prime is 221609617. The reversal of 221609601 is 106906122.

It can be written as a sum of positive squares in only one way, i.e., 150038001 + 71571600 = 12249^2 + 8460^2 .

It is not a de Polignac number, because 221609601 - 2¹ = 221609599 is a prime.

It is a super-2 number, since 2×221609601² = 98221630510758402, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (221609621) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1367880 + ... + 1368041.

Almost surely, 2^221609601 is an apocalyptic number.

It is an amenable number.

221609601 is a deficient number, since it is larger than the sum of its proper divisors (109436961).

221609601 is an equidigital number, since it uses as much as digits as its factorization.

221609601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2735933 (or 2735924 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 221609601 is about 14886.5577283669. The cubic root of 221609601 is about 605.1497486928.

The spelling of 221609601 in words is "two hundred twenty-one million, six hundred nine thousand, six hundred one".