81645077 has 2 divisors, whose sum is σ = 81645078. Its totient is φ = 81645076.

The previous prime is 81645073. The next prime is 81645079. The reversal of 81645077 is 77054618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43217476 + 38427601 = 6574^2 + 6199^2 .

It is a cyclic number.

It is not a de Polignac number, because 81645077 - 2² = 81645073 is a prime.

Together with 81645079, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_4759940 and since 81645077 and 4759940 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81645077.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81645073) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40822538 + 40822539.

It is an arithmetic number, because the mean of its divisors is an integer number (40822539).

Almost surely, 2^81645077 is an apocalyptic number.

It is an amenable number.

81645077 is a deficient number, since it is larger than the sum of its proper divisors (1).

81645077 is an equidigital number, since it uses as much as digits as its factorization.

81645077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47040, while the sum is 38.

The square root of 81645077 is about 9035.7665419155. The cubic root of 81645077 is about 433.8204305013.

The spelling of 81645077 in words is "eighty-one million, six hundred forty-five thousand, seventy-seven".