91388891 has 16 divisors (see below), whose sum is σ = 101189088. Its totient is φ = 81849600.

The previous prime is 91388833. The next prime is 91388897. The reversal of 91388891 is 19888319.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 91388891 - 2⁶ = 91388827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91388897) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 392111 + ... + 392343.

It is an arithmetic number, because the mean of its divisors is an integer number (6324318).

Almost surely, 2^91388891 is an apocalyptic number.

91388891 is a deficient number, since it is larger than the sum of its proper divisors (9800197).

91388891 is a wasteful number, since it uses less digits than its factorization.

91388891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622.

The product of its digits is 124416, while the sum is 47.

The square root of 91388891 is about 9559.7537102166. The cubic root of 91388891 is about 450.4339698321.

The spelling of 91388891 in words is "ninety-one million, three hundred eighty-eight thousand, eight hundred ninety-one".