161851718787 has 16 divisors (see below), whose sum is σ = 235427916288. Its totient is φ = 98088936480.

The previous prime is 161851718761. The next prime is 161851718807. The reversal of 161851718787 is 787817158161.

It is a happy number.

It is not a de Polignac number, because 161851718787 - 2⁶ = 161851718723 is a prime.

It is a super-2 number, since 2×161851718787² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161851718787.

It is not an unprimeable number, because it can be changed into a prime (161851718687) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1516998 + ... + 1620180.

It is an arithmetic number, because the mean of its divisors is an integer number (14714244768).

Almost surely, 2^161851718787 is an apocalyptic number.

161851718787 is a deficient number, since it is larger than the sum of its proper divisors (73576197501).

161851718787 is a wasteful number, since it uses less digits than its factorization.

161851718787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150730.

The product of its digits is 5268480, while the sum is 60.

The spelling of 161851718787 in words is "one hundred sixty-one billion, eight hundred fifty-one million, seven hundred eighteen thousand, seven hundred eighty-seven".