172121078 has 4 divisors (see below), whose sum is σ = 258181620. Its totient is φ = 86060538.

The previous prime is 172121071. The next prime is 172121093. The reversal of 172121078 is 870121271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 870121271 = 1231 ⋅706841.

It is a self number, because there is not a number n which added to its sum of digits gives 172121078.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172121071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43030268 + ... + 43030271.

It is an arithmetic number, because the mean of its divisors is an integer number (64545405).

Almost surely, 2^172121078 is an apocalyptic number.

172121078 is a deficient number, since it is larger than the sum of its proper divisors (86060542).

172121078 is an equidigital number, since it uses as much as digits as its factorization.

172121078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86060541.

The product of its (nonzero) digits is 1568, while the sum is 29.

The square root of 172121078 is about 13119.4922920058. The cubic root of 172121078 is about 556.2602403872.

The spelling of 172121078 in words is "one hundred seventy-two million, one hundred twenty-one thousand, seventy-eight".