91638481 has 4 divisors (see below), whose sum is σ = 99969264. Its totient is φ = 83307700.

The previous prime is 91638473. The next prime is 91638487. The reversal of 91638481 is 18483619.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 91638481 - 2³ = 91638473 is a prime.

It is a super-2 number, since 2×91638481² = 16795222399974722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91638487) 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, 4165375 + ... + 4165396.

It is an arithmetic number, because the mean of its divisors is an integer number (24992316).

Almost surely, 2^91638481 is an apocalyptic number.

It is an amenable number.

91638481 is a deficient number, since it is larger than the sum of its proper divisors (8330783).

91638481 is a wasteful number, since it uses less digits than its factorization.

91638481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8330782.

The product of its digits is 41472, while the sum is 40.

The square root of 91638481 is about 9572.7990159618. The cubic root of 91638481 is about 450.8436535560.

The spelling of 91638481 in words is "ninety-one million, six hundred thirty-eight thousand, four hundred eighty-one".