91618321 has 4 divisors (see below), whose sum is σ = 97007652. Its totient is φ = 86228992.

The previous prime is 91618309. The next prime is 91618333. The reversal of 91618321 is 12381619.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12381619 = 71 ⋅174389.

It is an interprime number because it is at equal distance from previous prime (91618309) and next prime (91618333).

It can be written as a sum of positive squares in 2 ways, for example, as 74304400 + 17313921 = 8620^2 + 4161^2 .

It is a cyclic number.

It is not a de Polignac number, because 91618321 - 2¹⁵ = 91585553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91618301) 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, 2694640 + ... + 2694673.

It is an arithmetic number, because the mean of its divisors is an integer number (24251913).

Almost surely, 2^91618321 is an apocalyptic number.

It is an amenable number.

91618321 is a deficient number, since it is larger than the sum of its proper divisors (5389331).

91618321 is a wasteful number, since it uses less digits than its factorization.

91618321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5389330.

The product of its digits is 2592, while the sum is 31.

The square root of 91618321 is about 9571.7459744814. The cubic root of 91618321 is about 450.8105900272.

The spelling of 91618321 in words is "ninety-one million, six hundred eighteen thousand, three hundred twenty-one".