639461261 has 2 divisors, whose sum is σ = 639461262. Its totient is φ = 639461260.

The previous prime is 639461243. The next prime is 639461267. The reversal of 639461261 is 162164936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 514155625 + 125305636 = 22675^2 + 11194^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639461261 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (639461267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319730630 + 319730631.

It is an arithmetic number, because the mean of its divisors is an integer number (319730631).

Almost surely, 2^639461261 is an apocalyptic number.

It is an amenable number.

639461261 is a deficient number, since it is larger than the sum of its proper divisors (1).

639461261 is an equidigital number, since it uses as much as digits as its factorization.

639461261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46656, while the sum is 38.

The square root of 639461261 is about 25287.5712752332. The cubic root of 639461261 is about 861.5320002167.

The spelling of 639461261 in words is "six hundred thirty-nine million, four hundred sixty-one thousand, two hundred sixty-one".