91279999 has 4 divisors (see below), whose sum is σ = 93747064. Its totient is φ = 88812936.

The previous prime is 91279961. The next prime is 91280011. The reversal of 91279999 is 99997219.

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

It is a cyclic number.

It is not a de Polignac number, because 91279999 - 2¹¹ = 91277951 is a prime.

It is a Duffinian number.

91279999 is a modest number, since divided by 9999 gives 9127 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91279099) 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, 1233477 + ... + 1233550.

It is an arithmetic number, because the mean of its divisors is an integer number (23436766).

Almost surely, 2^91279999 is an apocalyptic number.

91279999 is a deficient number, since it is larger than the sum of its proper divisors (2467065).

91279999 is a wasteful number, since it uses less digits than its factorization.

91279999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2467064.

The product of its digits is 826686, while the sum is 55.

The square root of 91279999 is about 9554.0566776632. The cubic root of 91279999 is about 450.2549978620.

The spelling of 91279999 in words is "ninety-one million, two hundred seventy-nine thousand, nine hundred ninety-nine".