91781705 has 4 divisors (see below), whose sum is σ = 110138052. Its totient is φ = 73425360.

The previous prime is 91781693. The next prime is 91781749. The reversal of 91781705 is 50718719.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19123129 + 72658576 = 4373^2 + 8524^2 .

It is not a de Polignac number, because 91781705 - 2¹⁴ = 91765321 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9178166 + ... + 9178175.

It is an arithmetic number, because the mean of its divisors is an integer number (27534513).

Almost surely, 2^91781705 is an apocalyptic number.

It is an amenable number.

91781705 is a deficient number, since it is larger than the sum of its proper divisors (18356347).

91781705 is a wasteful number, since it uses less digits than its factorization.

91781705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18356346.

The product of its (nonzero) digits is 17640, while the sum is 38.

The square root of 91781705 is about 9580.2768749134. The cubic root of 91781705 is about 451.0784094493.

The spelling of 91781705 in words is "ninety-one million, seven hundred eighty-one thousand, seven hundred five".