161121383281 has 4 divisors (see below), whose sum is σ = 161144576500. Its totient is φ = 161098190064.

The previous prime is 161121383279. The next prime is 161121383341. The reversal of 161121383281 is 182383121161.

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 132648195681 + 28473187600 = 364209^2 + 168740^2 .

It is a cyclic number.

It is not a de Polignac number, because 161121383281 - 2¹ = 161121383279 is a prime.

It is a super-2 number, since 2×161121383281² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 161121383281.

It is not an unprimeable number, because it can be changed into a prime (161121383201) 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, 11586186 + ... + 11600083.

It is an arithmetic number, because the mean of its divisors is an integer number (40286144125).

Almost surely, 2^161121383281 is an apocalyptic number.

It is an amenable number.

161121383281 is a deficient number, since it is larger than the sum of its proper divisors (23193219).

161121383281 is an equidigital number, since it uses as much as digits as its factorization.

161121383281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23193218.

The product of its digits is 13824, while the sum is 37.

The spelling of 161121383281 in words is "one hundred sixty-one billion, one hundred twenty-one million, three hundred eighty-three thousand, two hundred eighty-one".