172788561 has 24 divisors (see below), whose sum is σ = 288291744. Its totient is φ = 98559360.

The previous prime is 172788559. The next prime is 172788569. The reversal of 172788561 is 165887271.

It is a happy number.

172788561 is a `hidden beast` number, since 1 + 7 + 2 + 7 + 88 + 561 = 666.

It is not a de Polignac number, because 172788561 - 2¹ = 172788559 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (172788569) 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, 49651 + ... + 53016.

It is an arithmetic number, because the mean of its divisors is an integer number (12012156).

Almost surely, 2^172788561 is an apocalyptic number.

172788561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

172788561 is a deficient number, since it is larger than the sum of its proper divisors (115503183).

172788561 is a wasteful number, since it uses less digits than its factorization.

172788561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102701 (or 102698 counting only the distinct ones).

The product of its digits is 188160, while the sum is 45.

The square root of 172788561 is about 13144.9062758165. The cubic root of 172788561 is about 556.9783692219.

The spelling of 172788561 in words is "one hundred seventy-two million, seven hundred eighty-eight thousand, five hundred sixty-one".