172217021 has 8 divisors (see below), whose sum is σ = 186588864. Its totient is φ = 158316480.

The previous prime is 172217011. The next prime is 172217029. The reversal of 172217021 is 120712271.

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 172217021 - 2²² = 168022717 is a prime.

It is a super-2 number, since 2×172217021² = 59317404644228882, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172217029) 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, 117065 + ... + 118526.

It is an arithmetic number, because the mean of its divisors is an integer number (23323608).

Almost surely, 2^172217021 is an apocalyptic number.

It is an amenable number.

172217021 is a deficient number, since it is larger than the sum of its proper divisors (14371843).

172217021 is a wasteful number, since it uses less digits than its factorization.

172217021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 235651.

The product of its (nonzero) digits is 392, while the sum is 23.

The square root of 172217021 is about 13123.1482884253. The cubic root of 172217021 is about 556.3635772623.

Adding to 172217021 its reverse (120712271), we get a palindrome (292929292).

It can be divided in two parts, 17221 and 7021, that added together give a palindrome (24242).

The spelling of 172217021 in words is "one hundred seventy-two million, two hundred seventeen thousand, twenty-one".