161631787536 has 120 divisors (see below), whose sum is σ = 483891388344. Its totient is φ = 50185175040.

The previous prime is 161631787523. The next prime is 161631787609. The reversal of 161631787536 is 635787136161.

161631787536 is a `hidden beast` number, since 1 + 6 + 1 + 6 + 31 + 78 + 7 + 536 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 82702256400 + 78929531136 = 287580^2 + 280944^2 .

It is a super-2 number, since 2×161631787536² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 102885 + ... + 577796.

Almost surely, 2^161631787536 is an apocalyptic number.

161631787536 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161631787536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (241945694172).

161631787536 is an abundant number, since it is smaller than the sum of its proper divisors (322259600808).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161631787536 is a wasteful number, since it uses less digits than its factorization.

161631787536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680809 (or 680800 counting only the distinct ones).

The product of its digits is 3810240, while the sum is 54.

The spelling of 161631787536 in words is "one hundred sixty-one billion, six hundred thirty-one million, seven hundred eighty-seven thousand, five hundred thirty-six".