91983781 has 2 divisors, whose sum is σ = 91983782. Its totient is φ = 91983780.

The previous prime is 91983757. The next prime is 91983803. The reversal of 91983781 is 18738919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91872225 + 111556 = 9585^2 + 334^2 .

It is an emirp because it is prime and its reverse (18738919) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91983781 - 2¹³ = 91975589 is a prime.

It is a super-2 number, since 2×91983781² = 16922031934111922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91983701) 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 as a sum of consecutive naturals, namely, 45991890 + 45991891.

It is an arithmetic number, because the mean of its divisors is an integer number (45991891).

Almost surely, 2^91983781 is an apocalyptic number.

It is an amenable number.

91983781 is a deficient number, since it is larger than the sum of its proper divisors (1).

91983781 is an equidigital number, since it uses as much as digits as its factorization.

91983781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 46.

The square root of 91983781 is about 9590.8175355389. The cubic root of 91983781 is about 451.4092135958.

The spelling of 91983781 in words is "ninety-one million, nine hundred eighty-three thousand, seven hundred eighty-one".