1261681265018 has 8 divisors (see below), whose sum is σ = 1892528929620. Its totient is φ = 630838288480.

The previous prime is 1261681264999. The next prime is 1261681265023. The reversal of 1261681265018 is 8105621861621.

It can be written as a sum of positive squares in 2 ways, for example, as 1225863052969 + 35818212049 = 1107187^2 + 189257^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×1261681265018² (a number of 25 digits) contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 396593 + ... + 1637268.

Almost surely, 2^{1261681265018} is an apocalyptic number.

1261681265018 is a deficient number, since it is larger than the sum of its proper divisors (630847664602).

1261681265018 is a wasteful number, since it uses less digits than its factorization.

1261681265018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2344032.

The product of its (nonzero) digits is 276480, while the sum is 47.

The spelling of 1261681265018 in words is "one trillion, two hundred sixty-one billion, six hundred eighty-one million, two hundred sixty-five thousand, eighteen".