261164521128 has 64 divisors (see below), whose sum is σ = 785457216000. Its totient is φ = 70691147712.

The previous prime is 261164521091. The next prime is 261164521139. The reversal of 261164521128 is 821125461162.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40906038 + ... + 40912421.

It is an arithmetic number, because the mean of its divisors is an integer number (12272769000).

Almost surely, 2^261164521128 is an apocalyptic number.

261164521128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

261164521128 is an abundant number, since it is smaller than the sum of its proper divisors (524292694872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261164521128 is a wasteful number, since it uses less digits than its factorization.

261164521128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81818494 (or 81818490 counting only the distinct ones).

The product of its digits is 46080, while the sum is 39.

The spelling of 261164521128 in words is "two hundred sixty-one billion, one hundred sixty-four million, five hundred twenty-one thousand, one hundred twenty-eight".