81251783 has 2 divisors, whose sum is σ = 81251784. Its totient is φ = 81251782.

The previous prime is 81251683. The next prime is 81251813. The reversal of 81251783 is 38715218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81251783 - 2¹⁰ = 81250759 is a prime.

It is a super-3 number, since 3×81251783³ (a number of 25 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81251383) 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, 40625891 + 40625892.

It is an arithmetic number, because the mean of its divisors is an integer number (40625892).

Almost surely, 2^81251783 is an apocalyptic number.

81251783 is a deficient number, since it is larger than the sum of its proper divisors (1).

81251783 is an equidigital number, since it uses as much as digits as its factorization.

81251783 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 35.

The square root of 81251783 is about 9013.9770911624. The cubic root of 81251783 is about 433.1227208613.

The spelling of 81251783 in words is "eighty-one million, two hundred fifty-one thousand, seven hundred eighty-three".