181609474 has 4 divisors (see below), whose sum is σ = 272414214. Its totient is φ = 90804736.

The previous prime is 181609433. The next prime is 181609489. The reversal of 181609474 is 474906181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 474906181 = 1847 ⋅257123.

It can be written as a sum of positive squares in only one way, i.e., 137053849 + 44555625 = 11707^2 + 6675^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45402367 + ... + 45402370.

Almost surely, 2^181609474 is an apocalyptic number.

181609474 is a deficient number, since it is larger than the sum of its proper divisors (90804740).

181609474 is an equidigital number, since it uses as much as digits as its factorization.

181609474 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90804739.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 181609474 is about 13476.2559340493. The cubic root of 181609474 is about 566.2994852364.

The spelling of 181609474 in words is "one hundred eighty-one million, six hundred nine thousand, four hundred seventy-four".