172011021 has 24 divisors (see below), whose sum is σ = 287318304. Its totient is φ = 90730080.

The previous prime is 172011011. The next prime is 172011067. The reversal of 172011021 is 120110271.

It is not a de Polignac number, because 172011021 - 2⁵ = 172010989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172011001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43095 + ... + 46916.

It is an arithmetic number, because the mean of its divisors is an integer number (11971596).

Almost surely, 2^172011021 is an apocalyptic number.

It is an amenable number.

172011021 is a deficient number, since it is larger than the sum of its proper divisors (115307283).

172011021 is a wasteful number, since it uses less digits than its factorization.

172011021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90041 (or 90034 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 15.

The square root of 172011021 is about 13115.2972135594. The cubic root of 172011021 is about 556.1416545114.

Adding to 172011021 its reverse (120110271), we get a palindrome (292121292).

The spelling of 172011021 in words is "one hundred seventy-two million, eleven thousand, twenty-one".