172047221 has 2 divisors, whose sum is σ = 172047222. Its totient is φ = 172047220.

The previous prime is 172047217. The next prime is 172047233. The reversal of 172047221 is 122740271.

172047221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 171976996 + 70225 = 13114^2 + 265^2 .

It is an emirp because it is prime and its reverse (122740271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172047221 - 2² = 172047217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172047121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86023610 + 86023611.

It is an arithmetic number, because the mean of its divisors is an integer number (86023611).

Almost surely, 2^172047221 is an apocalyptic number.

It is an amenable number.

172047221 is a deficient number, since it is larger than the sum of its proper divisors (1).

172047221 is an equidigital number, since it uses as much as digits as its factorization.

172047221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 26.

The square root of 172047221 is about 13116.6772088056. The cubic root of 172047221 is about 556.1806654144.

Adding to 172047221 its reverse (122740271), we get a palindrome (294787492).

The spelling of 172047221 in words is "one hundred seventy-two million, forty-seven thousand, two hundred twenty-one".