641742581 has 2 divisors, whose sum is σ = 641742582. Its totient is φ = 641742580.

The previous prime is 641742547. The next prime is 641742583. The reversal of 641742581 is 185247146.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 603488356 + 38254225 = 24566^2 + 6185^2 .

It is a cyclic number.

It is not a de Polignac number, because 641742581 - 2¹⁰ = 641741557 is a prime.

It is a super-2 number, since 2×641742581² = 823667080537083122, which contains 22 as substring.

Together with 641742583, 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 (641742583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320871290 + 320871291.

It is an arithmetic number, because the mean of its divisors is an integer number (320871291).

Almost surely, 2^641742581 is an apocalyptic number.

It is an amenable number.

641742581 is a deficient number, since it is larger than the sum of its proper divisors (1).

641742581 is an equidigital number, since it uses as much as digits as its factorization.

641742581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 53760, while the sum is 38.

The square root of 641742581 is about 25332.6386505630. The cubic root of 641742581 is about 862.5553082505. Note that the first 3 decimals are identical.

The spelling of 641742581 in words is "six hundred forty-one million, seven hundred forty-two thousand, five hundred eighty-one".