178839509401921 has 27 divisors (see below), whose sum is σ = 187820776582491. Its totient is φ = 170280291129984.

The previous prime is 178839509401909. The next prime is 178839509401997. The reversal of 178839509401921 is 129104905938871.

The square root of 178839509401921 is 13373089.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 66320028851521 + 112519480550400 = 8143711^2 + 10607520^2 .

It is a de Polignac number, because none of the positive numbers 2^k-178839509401921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (178839509401321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 28310826255 + ... + 28310832571.

Almost surely, 2^{178839509401921} is an apocalyptic number.

178839509401921 is the 13373089-th square number.

178839509401921 is the 6686545-th centered octagonal number.

It is an amenable number.

178839509401921 is a deficient number, since it is larger than the sum of its proper divisors (8981267180570).

178839509401921 is an frugal number, since it uses more digits than its factorization.

178839509401921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12838 (or 6419 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 67.

The spelling of 178839509401921 in words is "one hundred seventy-eight trillion, eight hundred thirty-nine billion, five hundred nine million, four hundred one thousand, nine hundred twenty-one".