181661973 has 4 divisors (see below), whose sum is σ = 242215968. Its totient is φ = 121107980.

The previous prime is 181661959. The next prime is 181661999. The reversal of 181661973 is 379166181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 181661973 - 2⁵ = 181661941 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181661903) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30276993 + ... + 30276998.

It is an arithmetic number, because the mean of its divisors is an integer number (60553992).

Almost surely, 2^181661973 is an apocalyptic number.

It is an amenable number.

181661973 is a deficient number, since it is larger than the sum of its proper divisors (60553995).

181661973 is an equidigital number, since it uses as much as digits as its factorization.

181661973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60553994.

The product of its digits is 54432, while the sum is 42.

The square root of 181661973 is about 13478.2036265965. The cubic root of 181661973 is about 566.3540479045.

The spelling of 181661973 in words is "one hundred eighty-one million, six hundred sixty-one thousand, nine hundred seventy-three".