91778473 has 2 divisors, whose sum is σ = 91778474. Its totient is φ = 91778472.

The previous prime is 91778471. The next prime is 91778483. The reversal of 91778473 is 37487719.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72795024 + 18983449 = 8532^2 + 4357^2 .

It is an emirp because it is prime and its reverse (37487719) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91778473 - 2¹ = 91778471 is a prime.

Together with 91778471, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (91778471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45889236 + 45889237.

It is an arithmetic number, because the mean of its divisors is an integer number (45889237).

Almost surely, 2^91778473 is an apocalyptic number.

It is an amenable number.

91778473 is a deficient number, since it is larger than the sum of its proper divisors (1).

91778473 is an equidigital number, since it uses as much as digits as its factorization.

91778473 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 296352, while the sum is 46.

The square root of 91778473 is about 9580.1081935435. The cubic root of 91778473 is about 451.0731146304.

The spelling of 91778473 in words is "ninety-one million, seven hundred seventy-eight thousand, four hundred seventy-three".