261919979850 has 48 divisors (see below), whose sum is σ = 649592673408. Its totient is φ = 69841981440.

The previous prime is 261919979819. The next prime is 261919979903. The reversal of 261919979850 is 58979919162.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5961162 + ... + 6004938.

It is an arithmetic number, because the mean of its divisors is an integer number (13533180696).

Almost surely, 2^261919979850 is an apocalyptic number.

261919979850 is an abundant number, since it is smaller than the sum of its proper divisors (387672693558).

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

261919979850 is a wasteful number, since it uses less digits than its factorization.

261919979850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83679 (or 83674 counting only the distinct ones).

The product of its (nonzero) digits is 22044960, while the sum is 66.

The spelling of 261919979850 in words is "two hundred sixty-one billion, nine hundred nineteen million, nine hundred seventy-nine thousand, eight hundred fifty".