161578618 has 4 divisors (see below), whose sum is σ = 242367930. Its totient is φ = 80789308.

The previous prime is 161578597. The next prime is 161578619. The reversal of 161578618 is 816875161.

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., 152596609 + 8982009 = 12353^2 + 2997^2 .

It is a super-2 number, since 2×161578618² = 52215299589579848, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161578619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40394653 + ... + 40394656.

Almost surely, 2^161578618 is an apocalyptic number.

161578618 is a deficient number, since it is larger than the sum of its proper divisors (80789312).

161578618 is an equidigital number, since it uses as much as digits as its factorization.

161578618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80789311.

The product of its digits is 80640, while the sum is 43.

The square root of 161578618 is about 12711.3578346296. The cubic root of 161578618 is about 544.6631119449.

The spelling of 161578618 in words is "one hundred sixty-one million, five hundred seventy-eight thousand, six hundred eighteen".