1641516221 has 4 divisors (see below), whose sum is σ = 1681553244. Its totient is φ = 1601479200.

The previous prime is 1641516199. The next prime is 1641516241. The reversal of 1641516221 is 1226151461.

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 50623225 + 1590892996 = 7115^2 + 39886^2 .

It is a cyclic number.

It is not a de Polignac number, because 1641516221 - 2¹⁴ = 1641499837 is a prime.

It is a super-2 number, since 2×1641516221² = 5389151007612241682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641516241) 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, 20018450 + ... + 20018531.

It is an arithmetic number, because the mean of its divisors is an integer number (420388311).

Almost surely, 2^1641516221 is an apocalyptic number.

It is an amenable number.

1641516221 is a deficient number, since it is larger than the sum of its proper divisors (40037023).

1641516221 is an equidigital number, since it uses as much as digits as its factorization.

1641516221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40037022.

The product of its digits is 2880, while the sum is 29.

The square root of 1641516221 is about 40515.6293422674. The cubic root of 1641516221 is about 1179.6370187287.

Adding to 1641516221 its reverse (1226151461), we get a palindrome (2867667682).

The spelling of 1641516221 in words is "one billion, six hundred forty-one million, five hundred sixteen thousand, two hundred twenty-one".