161733278821 has 4 divisors (see below), whose sum is σ = 162023644332. Its totient is φ = 161442913312.

The previous prime is 161733278807. The next prime is 161733278911. The reversal of 161733278821 is 128872337161.

It is a happy number.

161733278821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 98697133921 + 63036144900 = 314161^2 + 251070^2 .

It is a cyclic number.

It is not a de Polignac number, because 161733278821 - 2¹⁷ = 161733147749 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 (161733278321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145181920 + ... + 145183033.

It is an arithmetic number, because the mean of its divisors is an integer number (40505911083).

Almost surely, 2^161733278821 is an apocalyptic number.

It is an amenable number.

161733278821 is a deficient number, since it is larger than the sum of its proper divisors (290365511).

161733278821 is an equidigital number, since it uses as much as digits as its factorization.

161733278821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290365510.

The product of its digits is 677376, while the sum is 49.

The spelling of 161733278821 in words is "one hundred sixty-one billion, seven hundred thirty-three million, two hundred seventy-eight thousand, eight hundred twenty-one".