161815537 has 8 divisors (see below), whose sum is σ = 184513896. Its totient is φ = 140581632.

The previous prime is 161815517. The next prime is 161815547. The reversal of 161815537 is 735518161.

It can be written as a sum of positive squares in 4 ways, for example, as 19633761 + 142181776 = 4431^2 + 11924^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161815537 - 2¹¹ = 161813489 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161815496 and 161815505.

It is not an unprimeable number, because it can be changed into a prime (161815517) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 365878 + ... + 366319.

It is an arithmetic number, because the mean of its divisors is an integer number (23064237).

Almost surely, 2^161815537 is an apocalyptic number.

161815537 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

161815537 is a deficient number, since it is larger than the sum of its proper divisors (22698359).

161815537 is a wasteful number, since it uses less digits than its factorization.

161815537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 732227.

The product of its digits is 25200, while the sum is 37.

The square root of 161815537 is about 12720.6736063779. The cubic root of 161815537 is about 544.9291909240.

The spelling of 161815537 in words is "one hundred sixty-one million, eight hundred fifteen thousand, five hundred thirty-seven".