172491866 has 4 divisors (see below), whose sum is σ = 258737802. Its totient is φ = 86245932.

The previous prime is 172491863. The next prime is 172491883. The reversal of 172491866 is 668194271.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 171217225 + 1274641 = 13085^2 + 1129^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (172491863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43122965 + ... + 43122968.

Almost surely, 2^172491866 is an apocalyptic number.

172491866 is a deficient number, since it is larger than the sum of its proper divisors (86245936).

172491866 is an equidigital number, since it uses as much as digits as its factorization.

172491866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86245935.

The product of its digits is 145152, while the sum is 44.

The square root of 172491866 is about 13133.6158768254. The cubic root of 172491866 is about 556.6593909830.

The spelling of 172491866 in words is "one hundred seventy-two million, four hundred ninety-one thousand, eight hundred sixty-six".