91811647 has 2 divisors, whose sum is σ = 91811648. Its totient is φ = 91811646.

The previous prime is 91811623. The next prime is 91811693. The reversal of 91811647 is 74611819.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91811647 - 2⁷ = 91811519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91811347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45905823 + 45905824.

It is an arithmetic number, because the mean of its divisors is an integer number (45905824).

Almost surely, 2^91811647 is an apocalyptic number.

91811647 is a deficient number, since it is larger than the sum of its proper divisors (1).

91811647 is an equidigital number, since it uses as much as digits as its factorization.

91811647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12096, while the sum is 37.

The square root of 91811647 is about 9581.8394371853. The cubic root of 91811647 is about 451.1274559752.

It can be divided in two parts, 9 and 1811647, that added together give a triangular number (1811656 = T₁₉₀₃).

The spelling of 91811647 in words is "ninety-one million, eight hundred eleven thousand, six hundred forty-seven".