1261364867491 has 2 divisors, whose sum is σ = 1261364867492. Its totient is φ = 1261364867490.

The previous prime is 1261364867461. The next prime is 1261364867561. The reversal of 1261364867491 is 1947684631621.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1261364867491 - 2²⁵ = 1261331313059 is a prime.

It is not a weakly prime, because it can be changed into another prime (1261364867461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630682433745 + 630682433746.

It is an arithmetic number, because the mean of its divisors is an integer number (630682433746).

Almost surely, 2^{1261364867491} is an apocalyptic number.

1261364867491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261364867491 is an equidigital number, since it uses as much as digits as its factorization.

1261364867491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10450944, while the sum is 58.

The spelling of 1261364867491 in words is "one trillion, two hundred sixty-one billion, three hundred sixty-four million, eight hundred sixty-seven thousand, four hundred ninety-one".