81965647 has 2 divisors, whose sum is σ = 81965648. Its totient is φ = 81965646.

The previous prime is 81965633. The next prime is 81965699. The reversal of 81965647 is 74656918.

It is a weak prime.

81965647 is a truncatable prime.

It is a cyclic number.

It is not a de Polignac number, because 81965647 - 2²³ = 73577039 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81965597 and 81965606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81965627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40982823 + 40982824.

It is an arithmetic number, because the mean of its divisors is an integer number (40982824).

Almost surely, 2^81965647 is an apocalyptic number.

81965647 is a deficient number, since it is larger than the sum of its proper divisors (1).

81965647 is an equidigital number, since it uses as much as digits as its factorization.

81965647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 362880, while the sum is 46.

The square root of 81965647 is about 9053.4881123244. The cubic root of 81965647 is about 434.3874710082.

It can be divided in two parts, 819 and 65647, that added together give a palindrome (66466).

The spelling of 81965647 in words is "eighty-one million, nine hundred sixty-five thousand, six hundred forty-seven".