172121128 has 16 divisors (see below), whose sum is σ = 323006580. Its totient is φ = 85986048.

The previous prime is 172121123. The next prime is 172121129. The reversal of 172121128 is 821121271.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 172081924 + 39204 = 13118^2 + 198^2 .

It is not an unprimeable number, because it can be changed into a prime (172121123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1200 + ... + 18592.

Almost surely, 2^172121128 is an apocalyptic number.

It is an amenable number.

172121128 is a deficient number, since it is larger than the sum of its proper divisors (150885452).

172121128 is a wasteful number, since it uses less digits than its factorization.

172121128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18636 (or 18632 counting only the distinct ones).

The product of its digits is 448, while the sum is 25.

The square root of 172121128 is about 13119.4941975672. The cubic root of 172121128 is about 556.2602942504.

Adding to 172121128 its reverse (821121271), we get a palindrome (993242399).

The spelling of 172121128 in words is "one hundred seventy-two million, one hundred twenty-one thousand, one hundred twenty-eight".