81998177 has 2 divisors, whose sum is σ = 81998178. Its totient is φ = 81998176.

The previous prime is 81998143. The next prime is 81998183. The reversal of 81998177 is 77189918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71081761 + 10916416 = 8431^2 + 3304^2 .

It is a cyclic number.

It is not a de Polignac number, because 81998177 - 2¹⁴ = 81981793 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81998977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40999088 + 40999089.

It is an arithmetic number, because the mean of its divisors is an integer number (40999089).

Almost surely, 2^81998177 is an apocalyptic number.

It is an amenable number.

81998177 is a deficient number, since it is larger than the sum of its proper divisors (1).

81998177 is an equidigital number, since it uses as much as digits as its factorization.

81998177 is an evil number, because the sum of its binary digits is even.

The product of its digits is 254016, while the sum is 50.

The square root of 81998177 is about 9055.2844792419. The cubic root of 81998177 is about 434.4449290450. Note that the first 3 decimals are identical.

The spelling of 81998177 in words is "eighty-one million, nine hundred ninety-eight thousand, one hundred seventy-seven".