78256491491 has 2 divisors, whose sum is σ = 78256491492. Its totient is φ = 78256491490.

The previous prime is 78256491479. The next prime is 78256491553. The reversal of 78256491491 is 19419465287.

It is a weak prime.

It is an emirp because it is prime and its reverse (19419465287) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78256491491 - 2²⁶ = 78189382627 is a prime.

It is a super-2 number, since 2×78256491491² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78256491461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39128245745 + 39128245746.

It is an arithmetic number, because the mean of its divisors is an integer number (39128245746).

Almost surely, 2^78256491491 is an apocalyptic number.

78256491491 is a deficient number, since it is larger than the sum of its proper divisors (1).

78256491491 is an equidigital number, since it uses as much as digits as its factorization.

78256491491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4354560, while the sum is 56.

The spelling of 78256491491 in words is "seventy-eight billion, two hundred fifty-six million, four hundred ninety-one thousand, four hundred ninety-one".