91781297 has 4 divisors (see below), whose sum is σ = 94742016. Its totient is φ = 88820580.

The previous prime is 91781279. The next prime is 91781309. The reversal of 91781297 is 79218719.

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, and also an emirpimes, since its reverse is a distinct semiprime: 79218719 = 919 ⋅86201.

It is not a de Polignac number, because 91781297 - 2¹⁴ = 91764913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91781227) 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, 1480313 + ... + 1480374.

It is an arithmetic number, because the mean of its divisors is an integer number (23685504).

Almost surely, 2^91781297 is an apocalyptic number.

It is an amenable number.

91781297 is a deficient number, since it is larger than the sum of its proper divisors (2960719).

91781297 is a wasteful number, since it uses less digits than its factorization.

91781297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2960718.

The product of its digits is 63504, while the sum is 44.

The square root of 91781297 is about 9580.2555811419. The cubic root of 91781297 is about 451.0777410508.

Subtracting from 91781297 its reverse (79218719), we obtain a triangular number (12562578 = T₅₀₁₂).

The spelling of 91781297 in words is "ninety-one million, seven hundred eighty-one thousand, two hundred ninety-seven".