161581139209 has 16 divisors (see below), whose sum is σ = 191349889920. Its totient is φ = 133499721600.

The previous prime is 161581139197. The next prime is 161581139227. The reversal of 161581139209 is 902931185161.

161581139209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161581139209 - 2²⁵ = 161547584777 is a prime.

It is a super-2 number, since 2×161581139209² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161581139299) 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 15 ways as a sum of consecutive naturals, for example, 540199 + ... + 784204.

It is an arithmetic number, because the mean of its divisors is an integer number (11959368120).

Almost surely, 2^161581139209 is an apocalyptic number.

It is an amenable number.

161581139209 is a deficient number, since it is larger than the sum of its proper divisors (29768750711).

161581139209 is a wasteful number, since it uses less digits than its factorization.

161581139209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1325040.

The product of its (nonzero) digits is 116640, while the sum is 46.

The spelling of 161581139209 in words is "one hundred sixty-one billion, five hundred eighty-one million, one hundred thirty-nine thousand, two hundred nine".