64781669 has 2 divisors, whose sum is σ = 64781670. Its totient is φ = 64781668.

The previous prime is 64781653. The next prime is 64781671. The reversal of 64781669 is 96618746.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64609444 + 172225 = 8038^2 + 415^2 .

It is a cyclic number.

It is not a de Polignac number, because 64781669 - 2⁴ = 64781653 is a prime.

It is a super-2 number, since 2×64781669² = 8393329276851122, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 64781671, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64781609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32390834 + 32390835.

It is an arithmetic number, because the mean of its divisors is an integer number (32390835).

Almost surely, 2^64781669 is an apocalyptic number.

It is an amenable number.

64781669 is a deficient number, since it is larger than the sum of its proper divisors (1).

64781669 is an equidigital number, since it uses as much as digits as its factorization.

64781669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 47.

The square root of 64781669 is about 8048.7060450733. The cubic root of 64781669 is about 401.6218918619.

The spelling of 64781669 in words is "sixty-four million, seven hundred eighty-one thousand, six hundred sixty-nine".