91778399 has 2 divisors, whose sum is σ = 91778400. Its totient is φ = 91778398.

The previous prime is 91778387. The next prime is 91778411. The reversal of 91778399 is 99387719.

It is a balanced prime because it is at equal distance from previous prime (91778387) and next prime (91778411).

It is an emirp because it is prime and its reverse (99387719) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91778399 - 2¹² = 91774303 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91778399.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91778339) 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, 45889199 + 45889200.

It is an arithmetic number, because the mean of its divisors is an integer number (45889200).

Almost surely, 2^91778399 is an apocalyptic number.

91778399 is a deficient number, since it is larger than the sum of its proper divisors (1).

91778399 is an equidigital number, since it uses as much as digits as its factorization.

91778399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 857304, while the sum is 53.

The square root of 91778399 is about 9580.1043313734. The cubic root of 91778399 is about 451.0729933986.

It can be divided in two parts, 9177 and 8399, that added together give a cube (17576 = 26³).

The spelling of 91778399 in words is "ninety-one million, seven hundred seventy-eight thousand, three hundred ninety-nine".