181664655461 has 4 divisors (see below), whose sum is σ = 186574511052. Its totient is φ = 176754799872.

The previous prime is 181664655401. The next prime is 181664655481. The reversal of 181664655461 is 164556466181.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 107289002500 + 74375652961 = 327550^2 + 272719^2 .

It is a cyclic number.

It is not a de Polignac number, because 181664655461 - 2²⁶ = 181597546597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181664655401) 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, 2454927740 + ... + 2454927813.

It is an arithmetic number, because the mean of its divisors is an integer number (46643627763).

Almost surely, 2^181664655461 is an apocalyptic number.

It is an amenable number.

181664655461 is a deficient number, since it is larger than the sum of its proper divisors (4909855591).

181664655461 is an equidigital number, since it uses as much as digits as its factorization.

181664655461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4909855590.

The product of its digits is 4147200, while the sum is 53.

The spelling of 181664655461 in words is "one hundred eighty-one billion, six hundred sixty-four million, six hundred fifty-five thousand, four hundred sixty-one".