1601216905 has 4 divisors (see below), whose sum is σ = 1921460292. Its totient is φ = 1280973520.

The previous prime is 1601216899. The next prime is 1601216959. The reversal of 1601216905 is 5096121061.

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 282946041 + 1318270864 = 16821^2 + 36308^2 .

It is not a de Polignac number, because 1601216905 - 2¹⁹ = 1600692617 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian 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, 160121686 + ... + 160121695.

It is an arithmetic number, because the mean of its divisors is an integer number (480365073).

Almost surely, 2^1601216905 is an apocalyptic number.

It is an amenable number.

1601216905 is a deficient number, since it is larger than the sum of its proper divisors (320243387).

1601216905 is an equidigital number, since it uses as much as digits as its factorization.

1601216905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320243386.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 1601216905 is about 40015.2084212990. The cubic root of 1601216905 is about 1169.9035411261.

Adding to 1601216905 its reverse (5096121061), we get a palindrome (6697337966).

The spelling of 1601216905 in words is "one billion, six hundred one million, two hundred sixteen thousand, nine hundred five".