81985151 has 2 divisors, whose sum is σ = 81985152. Its totient is φ = 81985150.

The previous prime is 81985147. The next prime is 81985177. The reversal of 81985151 is 15158918.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81985151 - 2² = 81985147 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81985121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40992575 + 40992576.

It is an arithmetic number, because the mean of its divisors is an integer number (40992576).

Almost surely, 2^81985151 is an apocalyptic number.

81985151 is a deficient number, since it is larger than the sum of its proper divisors (1).

81985151 is an equidigital number, since it uses as much as digits as its factorization.

81985151 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 38.

The square root of 81985151 is about 9054.5652021508. The cubic root of 81985151 is about 434.4219229265.

The spelling of 81985151 in words is "eighty-one million, nine hundred eighty-five thousand, one hundred fifty-one".