172111661 has 8 divisors (see below), whose sum is σ = 174230784. Its totient is φ = 170001360.

The previous prime is 172111631. The next prime is 172111729. The reversal of 172111661 is 166111271.

It is a happy number.

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 172111661 - 2²² = 167917357 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 172111661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172111631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42455 + ... + 46331.

It is an arithmetic number, because the mean of its divisors is an integer number (21778848).

Almost surely, 2^172111661 is an apocalyptic number.

It is an amenable number.

172111661 is a deficient number, since it is larger than the sum of its proper divisors (2119123).

172111661 is a wasteful number, since it uses less digits than its factorization.

172111661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4411.

The product of its digits is 504, while the sum is 26.

The square root of 172111661 is about 13119.1333936354. The cubic root of 172111661 is about 556.2500955940.

The spelling of 172111661 in words is "one hundred seventy-two million, one hundred eleven thousand, six hundred sixty-one".