78191873 has 2 divisors, whose sum is σ = 78191874. Its totient is φ = 78191872.

The previous prime is 78191849. The next prime is 78191899. The reversal of 78191873 is 37819187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56130064 + 22061809 = 7492^2 + 4697^2 .

It is a cyclic number.

It is not a de Polignac number, because 78191873 - 2¹⁸ = 77929729 is a prime.

It is a super-2 number, since 2×78191873² = 12227938006496258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78191843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39095936 + 39095937.

It is an arithmetic number, because the mean of its divisors is an integer number (39095937).

Almost surely, 2^78191873 is an apocalyptic number.

It is an amenable number.

78191873 is a deficient number, since it is larger than the sum of its proper divisors (1).

78191873 is an equidigital number, since it uses as much as digits as its factorization.

78191873 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 44.

The square root of 78191873 is about 8842.6168638023. The cubic root of 78191873 is about 427.6159265196.

The spelling of 78191873 in words is "seventy-eight million, one hundred ninety-one thousand, eight hundred seventy-three".