91913781 has 8 divisors (see below), whose sum is σ = 129760704. Its totient is φ = 57671360.

The previous prime is 91913753. The next prime is 91913797. The reversal of 91913781 is 18731919.

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

It is a cyclic number.

It is not a de Polignac number, because 91913781 - 2¹¹ = 91911733 is a prime.

It is a super-2 number, since 2×91913781² = 16896286275431922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91913281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 901065 + ... + 901166.

It is an arithmetic number, because the mean of its divisors is an integer number (16220088).

Almost surely, 2^91913781 is an apocalyptic number.

It is an amenable number.

91913781 is a deficient number, since it is larger than the sum of its proper divisors (37846923).

91913781 is a wasteful number, since it uses less digits than its factorization.

91913781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1802251.

The product of its digits is 13608, while the sum is 39.

The square root of 91913781 is about 9587.1675170511. The cubic root of 91913781 is about 451.2946765055.

The spelling of 91913781 in words is "ninety-one million, nine hundred thirteen thousand, seven hundred eighty-one".