1261711738791 has 72 divisors (see below), whose sum is σ = 2247655737600. Its totient is φ = 678117394080.

The previous prime is 1261711738787. The next prime is 1261711738883. The reversal of 1261711738791 is 1978371171621.

1261711738791 is a `hidden beast` number, since 1 + 2 + 6 + 171 + 1 + 7 + 387 + 91 = 666.

It is not a de Polignac number, because 1261711738791 - 2² = 1261711738787 is a prime.

It is a super-2 number, since 2×1261711738791² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261711728791) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 623026 + ... + 1706336.

It is an arithmetic number, because the mean of its divisors is an integer number (31217440800).

Almost surely, 2^{1261711738791} is an apocalyptic number.

1261711738791 is a deficient number, since it is larger than the sum of its proper divisors (985943998809).

1261711738791 is a wasteful number, since it uses less digits than its factorization.

1261711738791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1083489 (or 1083479 counting only the distinct ones).

The product of its digits is 889056, while the sum is 54.

The spelling of 1261711738791 in words is "one trillion, two hundred sixty-one billion, seven hundred eleven million, seven hundred thirty-eight thousand, seven hundred ninety-one".