91639 has 2 divisors, whose sum is σ = 91640.
Its totient is φ = 91638.
The previous prime is 91631. The next prime is 91673. The reversal of 91639 is 93619.
It is a happy number.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 91639 - 23 = 91631 is a prime.
91639 is a lucky number.
It is a plaindrome in base 14.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (91631) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45819 + 45820.
It is an arithmetic number, because the mean of its divisors is an integer number (45820).
291639 is an apocalyptic number.
91639 is a deficient number, since it is larger than the sum of its proper divisors (1).
91639 is an equidigital number, since it uses as much as digits as its factorization.
91639 is an evil number, because the sum of its binary digits is even.
The product of its digits is 1458, while the sum is 28.
The square root of 91639 is about 302.7193419655.
The cubic root of 91639 is about 45.0844504681.
The spelling of 91639 in words is "ninety-one thousand, six hundred thirty-nine".