1641320221 has 4 divisors (see below), whose sum is σ = 1697917500. Its totient is φ = 1584722944.

The previous prime is 1641320209. The next prime is 1641320231. The reversal of 1641320221 is 1220231461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1220231461 = 2753 ⋅443237.

It can be written as a sum of positive squares in 2 ways, for example, as 732297721 + 909022500 = 27061^2 + 30150^2 .

It is a cyclic number.

It is not a de Polignac number, because 1641320221 - 2⁵ = 1641320189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1641320192 and 1641320201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641320231) 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, 28298596 + ... + 28298653.

It is an arithmetic number, because the mean of its divisors is an integer number (424479375).

Almost surely, 2^1641320221 is an apocalyptic number.

It is an amenable number.

1641320221 is a deficient number, since it is larger than the sum of its proper divisors (56597279).

1641320221 is an equidigital number, since it uses as much as digits as its factorization.

1641320221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56597278.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 1641320221 is about 40513.2104504197. The cubic root of 1641320221 is about 1179.5900665968.

Adding to 1641320221 its reverse (1220231461), we get a palindrome (2861551682).

The spelling of 1641320221 in words is "one billion, six hundred forty-one million, three hundred twenty thousand, two hundred twenty-one".