261665603726340 has 48 divisors (see below), whose sum is σ = 799269480475200. Its totient is φ = 63434085751680.

The previous prime is 261665603726339. The next prime is 261665603726389. The reversal of 261665603726340 is 43627306566162.

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, 198231517315 + ... + 198231518634.

It is an arithmetic number, because the mean of its divisors is an integer number (16651447509900).

Almost surely, 2^{261665603726340} is an apocalyptic number.

261665603726340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261665603726340 is an abundant number, since it is smaller than the sum of its proper divisors (537603876748860).

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

261665603726340 is a wasteful number, since it uses less digits than its factorization.

261665603726340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 396463035972 (or 396463035970 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 57.

The spelling of 261665603726340 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, six hundred three million, seven hundred twenty-six thousand, three hundred forty".