1261391918105 has 16 divisors (see below), whose sum is σ = 1666709193024. Its totient is φ = 908802329280.

The previous prime is 1261391918077. The next prime is 1261391918113. The reversal of 1261391918105 is 5018191931621.

It is not a de Polignac number, because 1261391918105 - 2³⁴ = 1244212048921 is a prime.

It is a super-2 number, since 2×1261391918105² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1261391918105.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 107164202 + ... + 107175971.

It is an arithmetic number, because the mean of its divisors is an integer number (104169324564).

Almost surely, 2^{1261391918105} is an apocalyptic number.

It is an amenable number.

1261391918105 is a deficient number, since it is larger than the sum of its proper divisors (405317274919).

1261391918105 is a wasteful number, since it uses less digits than its factorization.

1261391918105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214340296.

The product of its (nonzero) digits is 116640, while the sum is 47.

The spelling of 1261391918105 in words is "one trillion, two hundred sixty-one billion, three hundred ninety-one million, nine hundred eighteen thousand, one hundred five".