161515665 has 24 divisors (see below), whose sum is σ = 282740328. Its totient is φ = 85286400.

The previous prime is 161515663. The next prime is 161515723. The reversal of 161515665 is 566515161.

It can be written as a sum of positive squares in 4 ways, for example, as 81216144 + 80299521 = 9012^2 + 8961^2 .

It is not a de Polignac number, because 161515665 - 2¹ = 161515663 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (161515663) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13224 + ... + 22313.

It is an arithmetic number, because the mean of its divisors is an integer number (11780847).

Almost surely, 2^161515665 is an apocalyptic number.

161515665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

161515665 is a deficient number, since it is larger than the sum of its proper divisors (121224663).

161515665 is a wasteful number, since it uses less digits than its factorization.

161515665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35649 (or 35646 counting only the distinct ones).

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

The square root of 161515665 is about 12708.8813433756. The cubic root of 161515665 is about 544.5923669595.

The spelling of 161515665 in words is "one hundred sixty-one million, five hundred fifteen thousand, six hundred sixty-five".