161256641305 has 8 divisors (see below), whose sum is σ = 194740505352. Its totient is φ = 128183622528.

The previous prime is 161256641303. The next prime is 161256641323. The reversal of 161256641305 is 503146652161.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6757333209 + 154499308096 = 82203^2 + 393064^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161256641305 - 2¹ = 161256641303 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161256641303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 102710452 + ... + 102712021.

It is an arithmetic number, because the mean of its divisors is an integer number (24342563169).

Almost surely, 2^161256641305 is an apocalyptic number.

It is an amenable number.

161256641305 is a deficient number, since it is larger than the sum of its proper divisors (33483864047).

161256641305 is a wasteful number, since it uses less digits than its factorization.

161256641305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205422635.

The product of its (nonzero) digits is 129600, while the sum is 40.

The spelling of 161256641305 in words is "one hundred sixty-one billion, two hundred fifty-six million, six hundred forty-one thousand, three hundred five".