161878857506 has 4 divisors (see below), whose sum is σ = 242818286262. Its totient is φ = 80939428752.

The previous prime is 161878857467. The next prime is 161878857521. The reversal of 161878857506 is 605758878161.

161878857506 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 147644220025 + 14234637481 = 384245^2 + 119309^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40469714375 + ... + 40469714378.

Almost surely, 2^161878857506 is an apocalyptic number.

161878857506 is a deficient number, since it is larger than the sum of its proper divisors (80939428756).

161878857506 is an equidigital number, since it uses as much as digits as its factorization.

161878857506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80939428755.

The product of its (nonzero) digits is 22579200, while the sum is 62.

The spelling of 161878857506 in words is "one hundred sixty-one billion, eight hundred seventy-eight million, eight hundred fifty-seven thousand, five hundred six".