91619681 has 8 divisors (see below), whose sum is σ = 97253640. Its totient is φ = 86012928.

The previous prime is 91619641. The next prime is 91619711. The reversal of 91619681 is 18691619.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 52432081 + 39187600 = 7241^2 + 6260^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91619681 - 2¹⁴ = 91603297 is a prime.

It is a super-2 number, since 2×91619681² = 16788331893083522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91619611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 365 + ... + 13541.

It is an arithmetic number, because the mean of its divisors is an integer number (12156705).

Almost surely, 2^91619681 is an apocalyptic number.

It is an amenable number.

91619681 is a deficient number, since it is larger than the sum of its proper divisors (5633959).

91619681 is a wasteful number, since it uses less digits than its factorization.

91619681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13603.

The product of its digits is 23328, while the sum is 41.

The square root of 91619681 is about 9571.8170166380. The cubic root of 91619681 is about 450.8128206559.

The spelling of 91619681 in words is "ninety-one million, six hundred nineteen thousand, six hundred eighty-one".