181668749 has 8 divisors (see below), whose sum is σ = 194991480. Its totient is φ = 168638976.

The previous prime is 181668733. The next prime is 181668761. The reversal of 181668749 is 947866181.

It can be written as a sum of positive squares in 4 ways, for example, as 59013124 + 122655625 = 7682^2 + 11075^2 .

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 181668749 - 2⁴ = 181668733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 181668697 and 181668706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181668349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71954 + ... + 74435.

It is an arithmetic number, because the mean of its divisors is an integer number (24373935).

Almost surely, 2^181668749 is an apocalyptic number.

It is an amenable number.

181668749 is a deficient number, since it is larger than the sum of its proper divisors (13322731).

181668749 is a wasteful number, since it uses less digits than its factorization.

181668749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146479.

The product of its digits is 580608, while the sum is 50.

The square root of 181668749 is about 13478.4549930621. The cubic root of 181668749 is about 566.3610894943.

The spelling of 181668749 in words is "one hundred eighty-one million, six hundred sixty-eight thousand, seven hundred forty-nine".