72173221 has 8 divisors (see below), whose sum is σ = 73968224. Its totient is φ = 70383600.

The previous prime is 72173219. The next prime is 72173251. The reversal of 72173221 is 12237127.

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 72173221 - 2¹ = 72173219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72173251) 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, 44395 + ... + 45991.

It is an arithmetic number, because the mean of its divisors is an integer number (9246028).

Almost surely, 2^72173221 is an apocalyptic number.

It is an amenable number.

72173221 is a deficient number, since it is larger than the sum of its proper divisors (1795003).

72173221 is a wasteful number, since it uses less digits than its factorization.

72173221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2691.

The product of its digits is 1176, while the sum is 25.

The square root of 72173221 is about 8495.4823877164. The cubic root of 72173221 is about 416.3501216769.

The spelling of 72173221 in words is "seventy-two million, one hundred seventy-three thousand, two hundred twenty-one".