78121565747 has 2 divisors, whose sum is σ = 78121565748. Its totient is φ = 78121565746.

The previous prime is 78121565719. The next prime is 78121565789. The reversal of 78121565747 is 74756512187.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78121565747 - 2²² = 78117371443 is a prime.

It is a super-2 number, since 2×78121565747² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78121565447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39060782873 + 39060782874.

It is an arithmetic number, because the mean of its divisors is an integer number (39060782874).

Almost surely, 2^78121565747 is an apocalyptic number.

78121565747 is a deficient number, since it is larger than the sum of its proper divisors (1).

78121565747 is an equidigital number, since it uses as much as digits as its factorization.

78121565747 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3292800, while the sum is 53.

The spelling of 78121565747 in words is "seventy-eight billion, one hundred twenty-one million, five hundred sixty-five thousand, seven hundred forty-seven".