639090649 has 2 divisors, whose sum is σ = 639090650. Its totient is φ = 639090648.

The previous prime is 639090643. The next prime is 639090671. The reversal of 639090649 is 946090936.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 388090000 + 251000649 = 19700^2 + 15843^2 .

It is a cyclic number.

It is not a de Polignac number, because 639090649 - 2⁷ = 639090521 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639090599 and 639090608.

It is not a weakly prime, because it can be changed into another prime (639090643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319545324 + 319545325.

It is an arithmetic number, because the mean of its divisors is an integer number (319545325).

Almost surely, 2^639090649 is an apocalyptic number.

It is an amenable number.

639090649 is a deficient number, since it is larger than the sum of its proper divisors (1).

639090649 is an equidigital number, since it uses as much as digits as its factorization.

639090649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 314928, while the sum is 46.

The square root of 639090649 is about 25280.2422654531. The cubic root of 639090649 is about 861.3655289377.

The spelling of 639090649 in words is "six hundred thirty-nine million, ninety thousand, six hundred forty-nine".