81617477 has 2 divisors, whose sum is σ = 81617478. Its totient is φ = 81617476.

The previous prime is 81617467. The next prime is 81617479. The reversal of 81617477 is 77471618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47348161 + 34269316 = 6881^2 + 5854^2 .

It is a cyclic number.

It is not a de Polignac number, because 81617477 - 2⁶ = 81617413 is a prime.

It is a super-2 number, since 2×81617477² = 13322825103691058, which contains 22 as substring.

Together with 81617479, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81617479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40808738 + 40808739.

It is an arithmetic number, because the mean of its divisors is an integer number (40808739).

Almost surely, 2^81617477 is an apocalyptic number.

It is an amenable number.

81617477 is a deficient number, since it is larger than the sum of its proper divisors (1).

81617477 is an equidigital number, since it uses as much as digits as its factorization.

81617477 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 65856, while the sum is 41.

The square root of 81617477 is about 9034.2391489267. The cubic root of 81617477 is about 433.7715408692.

The spelling of 81617477 in words is "eighty-one million, six hundred seventeen thousand, four hundred seventy-seven".