161591136257 has 8 divisors (see below), whose sum is σ = 163917556584. Its totient is φ = 159267765888.

The previous prime is 161591136229. The next prime is 161591136313. The reversal of 161591136257 is 752631195161.

It is a Cunningham number, because it is equal to 401984²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 66376308496 + 95214827761 = 257636^2 + 308569^2 .

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 161591136257 - 2⁸ = 161591136001 is a prime.

It is a super-2 number, since 2×161591136257² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161591136227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 655658 + ... + 867795.

It is an arithmetic number, because the mean of its divisors is an integer number (20489694573).

Almost surely, 2^161591136257 is an apocalyptic number.

It is an amenable number.

161591136257 is a deficient number, since it is larger than the sum of its proper divisors (2326420327).

161591136257 is a wasteful number, since it uses less digits than its factorization.

161591136257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1524979.

The product of its digits is 340200, while the sum is 47.

The spelling of 161591136257 in words is "one hundred sixty-one billion, five hundred ninety-one million, one hundred thirty-six thousand, two hundred fifty-seven".