65781613 has 2 divisors, whose sum is σ = 65781614. Its totient is φ = 65781612.

The previous prime is 65781593. The next prime is 65781631. The reversal of 65781613 is 31618756.

Together with next prime (65781631) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47914084 + 17867529 = 6922^2 + 4227^2 .

It is a cyclic number.

It is not a de Polignac number, because 65781613 - 2²¹ = 63684461 is a prime.

It is equal to p_3883915 and since 65781613 and 3883915 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65781113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32890806 + 32890807.

It is an arithmetic number, because the mean of its divisors is an integer number (32890807).

Almost surely, 2^65781613 is an apocalyptic number.

It is an amenable number.

65781613 is a deficient number, since it is larger than the sum of its proper divisors (1).

65781613 is an equidigital number, since it uses as much as digits as its factorization.

65781613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 37.

The square root of 65781613 is about 8110.5864769448. The cubic root of 65781613 is about 403.6777750400.

The spelling of 65781613 in words is "sixty-five million, seven hundred eighty-one thousand, six hundred thirteen".