91287891 has 10 divisors (see below), whose sum is σ = 136368452. Its totient is φ = 60858540.

The previous prime is 91287883. The next prime is 91287899. The reversal of 91287891 is 19878219.

It is an interprime number because it is at equal distance from previous prime (91287883) and next prime (91287899).

It is not a de Polignac number, because 91287891 - 2³ = 91287883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91287899) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 563425 + ... + 563586.

Almost surely, 2^91287891 is an apocalyptic number.

91287891 is a deficient number, since it is larger than the sum of its proper divisors (45080561).

91287891 is a wasteful number, since it uses less digits than its factorization.

91287891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127023 (or 1127014 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 91287891 is about 9554.4696870104. The cubic root of 91287891 is about 450.2679737241.

The spelling of 91287891 in words is "ninety-one million, two hundred eighty-seven thousand, eight hundred ninety-one".