78121847 has 2 divisors, whose sum is σ = 78121848. Its totient is φ = 78121846.

The previous prime is 78121843. The next prime is 78121859. The reversal of 78121847 is 74812187.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78121847 - 2² = 78121843 is a prime.

It is a super-2 number, since 2×78121847² = 12206045957382818, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 78121847.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78121843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39060923 + 39060924.

It is an arithmetic number, because the mean of its divisors is an integer number (39060924).

Almost surely, 2^78121847 is an apocalyptic number.

78121847 is a deficient number, since it is larger than the sum of its proper divisors (1).

78121847 is an equidigital number, since it uses as much as digits as its factorization.

78121847 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25088, while the sum is 38.

The square root of 78121847 is about 8838.6564024177. The cubic root of 78121847 is about 427.4882356007.

The spelling of 78121847 in words is "seventy-eight million, one hundred twenty-one thousand, eight hundred forty-seven".