65780809 has 2 divisors, whose sum is σ = 65780810. Its totient is φ = 65780808.

The previous prime is 65780797. The next prime is 65780833. The reversal of 65780809 is 90808756.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37393225 + 28387584 = 6115^2 + 5328^2 .

It is a cyclic number.

It is not a de Polignac number, because 65780809 - 2⁷ = 65780681 is a prime.

It is a super-2 number, since 2×65780809² = 8654229665388962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (65780839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32890404 + 32890405.

It is an arithmetic number, because the mean of its divisors is an integer number (32890405).

Almost surely, 2^65780809 is an apocalyptic number.

It is an amenable number.

65780809 is a deficient number, since it is larger than the sum of its proper divisors (1).

65780809 is an equidigital number, since it uses as much as digits as its factorization.

65780809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 120960, while the sum is 43.

The square root of 65780809 is about 8110.5369119436. The cubic root of 65780809 is about 403.6761304150.

The spelling of 65780809 in words is "sixty-five million, seven hundred eighty thousand, eight hundred nine".