91731559 has 4 divisors (see below), whose sum is σ = 91767880. Its totient is φ = 91695240.

The previous prime is 91731539. The next prime is 91731583. The reversal of 91731559 is 95513719.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 95513719 = 7 ⋅13644817.

It is a cyclic number.

It is not a de Polignac number, because 91731559 - 2¹⁹ = 91207271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91731539) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14064 + ... + 19525.

It is an arithmetic number, because the mean of its divisors is an integer number (22941970).

Almost surely, 2^91731559 is an apocalyptic number.

91731559 is a deficient number, since it is larger than the sum of its proper divisors (36321).

91731559 is a wasteful number, since it uses less digits than its factorization.

91731559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36320.

The product of its digits is 42525, while the sum is 40.

The square root of 91731559 is about 9577.6593695955. The cubic root of 91731559 is about 450.9962438417.

The spelling of 91731559 in words is "ninety-one million, seven hundred thirty-one thousand, five hundred fifty-nine".