91491663 has 4 divisors (see below), whose sum is σ = 121988888. Its totient is φ = 60994440.

The previous prime is 91491641. The next prime is 91491667. The reversal of 91491663 is 36619419.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36619419 = 3 ⋅12206473.

It is not a de Polignac number, because 91491663 - 2¹³ = 91483471 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 (91491667) 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, 15248608 + ... + 15248613.

It is an arithmetic number, because the mean of its divisors is an integer number (30497222).

Almost surely, 2^91491663 is an apocalyptic number.

91491663 is a deficient number, since it is larger than the sum of its proper divisors (30497225).

91491663 is a wasteful number, since it uses less digits than its factorization.

91491663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30497224.

The product of its digits is 34992, while the sum is 39.

The square root of 91491663 is about 9565.1274429565. The cubic root of 91491663 is about 450.6027527758.

The spelling of 91491663 in words is "ninety-one million, four hundred ninety-one thousand, six hundred sixty-three".