172500721 has 2 divisors, whose sum is σ = 172500722. Its totient is φ = 172500720.

The previous prime is 172500703. The next prime is 172500733. The reversal of 172500721 is 127005271.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166926400 + 5574321 = 12920^2 + 2361^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-172500721 is a prime.

It is not a weakly prime, because it can be changed into another prime (172500701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86250360 + 86250361.

It is an arithmetic number, because the mean of its divisors is an integer number (86250361).

Almost surely, 2^172500721 is an apocalyptic number.

It is an amenable number.

172500721 is a deficient number, since it is larger than the sum of its proper divisors (1).

172500721 is an equidigital number, since it uses as much as digits as its factorization.

172500721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 172500721 is about 13133.9529845359. The cubic root of 172500721 is about 556.6689163299.

Adding to 172500721 its reverse (127005271), we get a palindrome (299505992).

The spelling of 172500721 in words is "one hundred seventy-two million, five hundred thousand, seven hundred twenty-one".