161256337778 has 4 divisors (see below), whose sum is σ = 241884506670. Its totient is φ = 80628168888.

The previous prime is 161256337751. The next prime is 161256337789. The reversal of 161256337778 is 877733652161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 877733652161 = 79 ⋅11110552559.

It can be written as a sum of positive squares in only one way, i.e., 152925577249 + 8330760529 = 391057^2 + 91273^2 .

It is a Curzon number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 40314084443 + ... + 40314084446.

Almost surely, 2^161256337778 is an apocalyptic number.

161256337778 is a deficient number, since it is larger than the sum of its proper divisors (80628168892).

161256337778 is an equidigital number, since it uses as much as digits as its factorization.

161256337778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80628168891.

The product of its digits is 8890560, while the sum is 56.

The spelling of 161256337778 in words is "one hundred sixty-one billion, two hundred fifty-six million, three hundred thirty-seven thousand, seven hundred seventy-eight".