261888134478 has 16 divisors (see below), whose sum is σ = 540672278016. Its totient is φ = 84480043320.

The previous prime is 261888134461. The next prime is 261888134503. The reversal of 261888134478 is 874431888162.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 704000176 + ... + 704000547.

It is an arithmetic number, because the mean of its divisors is an integer number (33792017376).

Almost surely, 2^261888134478 is an apocalyptic number.

261888134478 is an abundant number, since it is smaller than the sum of its proper divisors (278784143538).

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

261888134478 is a wasteful number, since it uses less digits than its factorization.

261888134478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1408000759.

The product of its digits is 16515072, while the sum is 60.

The spelling of 261888134478 in words is "two hundred sixty-one billion, eight hundred eighty-eight million, one hundred thirty-four thousand, four hundred seventy-eight".