641666429 has 2 divisors, whose sum is σ = 641666430. Its totient is φ = 641666428.

The previous prime is 641666401. The next prime is 641666447. The reversal of 641666429 is 924666146.

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., 630763225 + 10903204 = 25115^2 + 3302^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641666429 is a prime.

It is a super-2 number, since 2×641666429² = 823471612211224082, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 641666429.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (641666449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320833214 + 320833215.

It is an arithmetic number, because the mean of its divisors is an integer number (320833215).

Almost surely, 2^641666429 is an apocalyptic number.

It is an amenable number.

641666429 is a deficient number, since it is larger than the sum of its proper divisors (1).

641666429 is an equidigital number, since it uses as much as digits as its factorization.

641666429 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 44.

The square root of 641666429 is about 25331.1355647551. The cubic root of 641666429 is about 862.5211886974.

The spelling of 641666429 in words is "six hundred forty-one million, six hundred sixty-six thousand, four hundred twenty-nine".