261895220018 has 16 divisors (see below), whose sum is σ = 395038680000. Its totient is φ = 130216399632.

The previous prime is 261895219997. The next prime is 261895220033. The reversal of 261895220018 is 810022598162.

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 7 ways as a sum of consecutive naturals, for example, 528113 + ... + 895931.

It is an arithmetic number, because the mean of its divisors is an integer number (24689917500).

Almost surely, 2^261895220018 is an apocalyptic number.

261895220018 is a deficient number, since it is larger than the sum of its proper divisors (133143459982).

261895220018 is a wasteful number, since it uses less digits than its factorization.

261895220018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369809.

The product of its (nonzero) digits is 138240, while the sum is 44.

The spelling of 261895220018 in words is "two hundred sixty-one billion, eight hundred ninety-five million, two hundred twenty thousand, eighteen".