915172221 has 8 divisors (see below), whose sum is σ = 1284452320. Its totient is φ = 578003472.

The previous prime is 915172189. The next prime is 915172243. The reversal of 915172221 is 122271519.

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

It is not a de Polignac number, because 915172221 - 2⁵ = 915172189 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 (915172721) 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, 8027770 + ... + 8027883.

It is an arithmetic number, because the mean of its divisors is an integer number (160556540).

Almost surely, 2^915172221 is an apocalyptic number.

It is an amenable number.

915172221 is a deficient number, since it is larger than the sum of its proper divisors (369280099).

915172221 is a wasteful number, since it uses less digits than its factorization.

915172221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16055675.

The product of its digits is 2520, while the sum is 30.

The square root of 915172221 is about 30251.8135158869. The cubic root of 915172221 is about 970.8845939045.

The spelling of 915172221 in words is "nine hundred fifteen million, one hundred seventy-two thousand, two hundred twenty-one".