91981706 has 4 divisors (see below), whose sum is σ = 137972562. Its totient is φ = 45990852.

The previous prime is 91981699. The next prime is 91981709. The reversal of 91981706 is 60718919.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 60718919 = 23 ⋅2639953.

It can be written as a sum of positive squares in only one way, i.e., 58446025 + 33535681 = 7645^2 + 5791^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (91981709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22995425 + ... + 22995428.

Almost surely, 2^91981706 is an apocalyptic number.

91981706 is a deficient number, since it is larger than the sum of its proper divisors (45990856).

91981706 is a wasteful number, since it uses less digits than its factorization.

91981706 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45990855.

The product of its (nonzero) digits is 27216, while the sum is 41.

The square root of 91981706 is about 9590.7093585407. The cubic root of 91981706 is about 451.4058192251.

The spelling of 91981706 in words is "ninety-one million, nine hundred eighty-one thousand, seven hundred six".