78191947 has 2 divisors, whose sum is σ = 78191948. Its totient is φ = 78191946.

The previous prime is 78191923. The next prime is 78191977. The reversal of 78191947 is 74919187.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78191947 - 2²³ = 69803339 is a prime.

It is a super-2 number, since 2×78191947² = 12227961151301618, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 78191897 and 78191906.

It is not a weakly prime, because it can be changed into another prime (78191977) 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, 39095973 + 39095974.

It is an arithmetic number, because the mean of its divisors is an integer number (39095974).

Almost surely, 2^78191947 is an apocalyptic number.

78191947 is a deficient number, since it is larger than the sum of its proper divisors (1).

78191947 is an equidigital number, since it uses as much as digits as its factorization.

78191947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 127008, while the sum is 46.

The square root of 78191947 is about 8842.6210480830. The cubic root of 78191947 is about 427.6160614167.

The spelling of 78191947 in words is "seventy-eight million, one hundred ninety-one thousand, nine hundred forty-seven".