639467281 has 2 divisors, whose sum is σ = 639467282. Its totient is φ = 639467280.

The previous prime is 639467267. The next prime is 639467327. The reversal of 639467281 is 182764936.

It is an a-pointer prime, because the next prime (639467327) can be obtained adding 639467281 to its sum of digits (46).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 635796225 + 3671056 = 25215^2 + 1916^2 .

It is a cyclic number.

It is not a de Polignac number, because 639467281 - 2²⁹ = 102596369 is a prime.

It is a super-2 number, since 2×639467281² = 817836806939065922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (639467261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319733640 + 319733641.

It is an arithmetic number, because the mean of its divisors is an integer number (319733641).

Almost surely, 2^639467281 is an apocalyptic number.

It is an amenable number.

639467281 is a deficient number, since it is larger than the sum of its proper divisors (1).

639467281 is an equidigital number, since it uses as much as digits as its factorization.

639467281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 435456, while the sum is 46.

The square root of 639467281 is about 25287.6903057594. The cubic root of 639467281 is about 861.5347037458.

The spelling of 639467281 in words is "six hundred thirty-nine million, four hundred sixty-seven thousand, two hundred eighty-one".