641779381 has 2 divisors, whose sum is σ = 641779382. Its totient is φ = 641779380.

The previous prime is 641779363. The next prime is 641779417. The reversal of 641779381 is 183977146.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 501356881 + 140422500 = 22391^2 + 11850^2 .

It is a cyclic number.

It is not a de Polignac number, because 641779381 - 2⁷ = 641779253 is a prime.

It is a super-2 number, since 2×641779381² = 823761547753486322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641779181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320889690 + 320889691.

It is an arithmetic number, because the mean of its divisors is an integer number (320889691).

Almost surely, 2^641779381 is an apocalyptic number.

It is an amenable number.

641779381 is a deficient number, since it is larger than the sum of its proper divisors (1).

641779381 is an equidigital number, since it uses as much as digits as its factorization.

641779381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 254016, while the sum is 46.

The square root of 641779381 is about 25333.3649758574. The cubic root of 641779381 is about 862.5717953538.

The spelling of 641779381 in words is "six hundred forty-one million, seven hundred seventy-nine thousand, three hundred eighty-one".