161519445881 has 4 divisors (see below), whose sum is σ = 161520249972. Its totient is φ = 161518641792.

The previous prime is 161519445863. The next prime is 161519445887. The reversal of 161519445881 is 188544915161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 118966357225 + 42553088656 = 344915^2 + 206284^2 .

It is a cyclic number.

It is not a de Polignac number, because 161519445881 - 2¹⁴ = 161519429497 is a prime.

It is a super-2 number, since 2×161519445881² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161519445887) 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, 184541 + ... + 597573.

It is an arithmetic number, because the mean of its divisors is an integer number (40380062493).

Almost surely, 2^161519445881 is an apocalyptic number.

It is an amenable number.

161519445881 is a deficient number, since it is larger than the sum of its proper divisors (804091).

161519445881 is an equidigital number, since it uses as much as digits as its factorization.

161519445881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804090.

The product of its digits is 1382400, while the sum is 53.

The spelling of 161519445881 in words is "one hundred sixty-one billion, five hundred nineteen million, four hundred forty-five thousand, eight hundred eighty-one".