81855377 has 2 divisors, whose sum is σ = 81855378. Its totient is φ = 81855376.

The previous prime is 81855337. The next prime is 81855419. The reversal of 81855377 is 77355818.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49547521 + 32307856 = 7039^2 + 5684^2 .

It is a cyclic number.

It is not a de Polignac number, because 81855377 - 2⁸ = 81855121 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81855317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40927688 + 40927689.

It is an arithmetic number, because the mean of its divisors is an integer number (40927689).

Almost surely, 2^81855377 is an apocalyptic number.

It is an amenable number.

81855377 is a deficient number, since it is larger than the sum of its proper divisors (1).

81855377 is an equidigital number, since it uses as much as digits as its factorization.

81855377 is an evil number, because the sum of its binary digits is even.

The product of its digits is 235200, while the sum is 44.

The square root of 81855377 is about 9047.3961447479. The cubic root of 81855377 is about 434.1925869135.

The spelling of 81855377 in words is "eighty-one million, eight hundred fifty-five thousand, three hundred seventy-seven".