161006561505 has 24 divisors (see below), whose sum is σ = 285884824680. Its totient is φ = 83775770880.

The previous prime is 161006561491. The next prime is 161006561561. The reversal of 161006561505 is 505165600161.

It can be written as a sum of positive squares in 4 ways, for example, as 20968198416 + 140038363089 = 144804^2 + 374217^2 .

It is not a de Polignac number, because 161006561505 - 2⁸ = 161006561249 is a prime.

It is a super-2 number, since 2×161006561505² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 161006561505.

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, 43631370 + ... + 43635059.

It is an arithmetic number, because the mean of its divisors is an integer number (11911867695).

Almost surely, 2^161006561505 is an apocalyptic number.

161006561505 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

161006561505 is a deficient number, since it is larger than the sum of its proper divisors (124878263175).

161006561505 is a wasteful number, since it uses less digits than its factorization.

161006561505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87266481 (or 87266478 counting only the distinct ones).

The product of its (nonzero) digits is 27000, while the sum is 36.

The spelling of 161006561505 in words is "one hundred sixty-one billion, six million, five hundred sixty-one thousand, five hundred five".