172206221 has 8 divisors (see below), whose sum is σ = 196029504. Its totient is φ = 149744320.

The previous prime is 172206211. The next prime is 172206239. The reversal of 172206221 is 122602271.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 172206221 - 2¹⁰ = 172205197 is a prime.

It is a super-2 number, since 2×172206221² = 59309965102201682, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172206211) 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, 340076 + ... + 340581.

It is an arithmetic number, because the mean of its divisors is an integer number (24503688).

Almost surely, 2^172206221 is an apocalyptic number.

172206221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

172206221 is a deficient number, since it is larger than the sum of its proper divisors (23823283).

172206221 is a wasteful number, since it uses less digits than its factorization.

172206221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680691.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 172206221 is about 13122.7367953488. The cubic root of 172206221 is about 556.3519468744.

Adding to 172206221 its reverse (122602271), we get a palindrome (294808492).

The spelling of 172206221 in words is "one hundred seventy-two million, two hundred six thousand, two hundred twenty-one".