161781625 has 8 divisors (see below), whose sum is σ = 201903624. Its totient is φ = 129425200.

The previous prime is 161781623. The next prime is 161781643. The reversal of 161781625 is 526187161.

It can be written as a sum of positive squares in 4 ways, for example, as 59536 + 161722089 = 244^2 + 12717^2 .

It is not a de Polignac number, because 161781625 - 2¹ = 161781623 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161781623) 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, 647002 + ... + 647251.

It is an arithmetic number, because the mean of its divisors is an integer number (25237953).

Almost surely, 2^161781625 is an apocalyptic number.

It is an amenable number.

161781625 is a deficient number, since it is larger than the sum of its proper divisors (40121999).

161781625 is an equidigital number, since it uses as much as digits as its factorization.

161781625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1294268 (or 1294258 counting only the distinct ones).

The product of its digits is 20160, while the sum is 37.

The square root of 161781625 is about 12719.3405882538. The cubic root of 161781625 is about 544.8911209707.

The spelling of 161781625 in words is "one hundred sixty-one million, seven hundred eighty-one thousand, six hundred twenty-five".