641299781 has 2 divisors, whose sum is σ = 641299782. Its totient is φ = 641299780.

The previous prime is 641299751. The next prime is 641299783. The reversal of 641299781 is 187992146.

641299781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 438693025 + 202606756 = 20945^2 + 14234^2 .

It is a cyclic number.

It is not a de Polignac number, because 641299781 - 2²² = 637105477 is a prime.

It is a super-2 number, since 2×641299781² = 822530818221295922, which contains 22 as substring.

Together with 641299783, 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 (641299783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320649890 + 320649891.

It is an arithmetic number, because the mean of its divisors is an integer number (320649891).

Almost surely, 2^641299781 is an apocalyptic number.

It is an amenable number.

641299781 is a deficient number, since it is larger than the sum of its proper divisors (1).

641299781 is an equidigital number, since it uses as much as digits as its factorization.

641299781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 47.

The square root of 641299781 is about 25323.8974291083. The cubic root of 641299781 is about 862.3568759501.

The spelling of 641299781 in words is "six hundred forty-one million, two hundred ninety-nine thousand, seven hundred eighty-one".