1291639823991 has 48 divisors (see below), whose sum is σ = 2126633812992. Its totient is φ = 747778680000.

The previous prime is 1291639823989. The next prime is 1291639823993. The reversal of 1291639823991 is 1993289361921.

1291639823991 is a `hidden beast` number, since 1 + 2 + 9 + 1 + 6 + 398 + 239 + 9 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (1291639823989) and next prime (1291639823993).

It is not a de Polignac number, because 1291639823991 - 2¹ = 1291639823989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291639823993) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1332361 + ... + 2087693.

It is an arithmetic number, because the mean of its divisors is an integer number (44304871104).

Almost surely, 2^{1291639823991} is an apocalyptic number.

1291639823991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1291639823991 is a deficient number, since it is larger than the sum of its proper divisors (834993989001).

1291639823991 is a wasteful number, since it uses less digits than its factorization.

1291639823991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756124 (or 756121 counting only the distinct ones).

The product of its digits is 11337408, while the sum is 63.

The spelling of 1291639823991 in words is "one trillion, two hundred ninety-one billion, six hundred thirty-nine million, eight hundred twenty-three thousand, nine hundred ninety-one".