639754649 has 2 divisors, whose sum is σ = 639754650. Its totient is φ = 639754648.

The previous prime is 639754631. The next prime is 639754651. The reversal of 639754649 is 946457936.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 385926025 + 253828624 = 19645^2 + 15932^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639754649 is a prime.

It is a super-2 number, since 2×639754649² = 818572021834226402, which contains 22 as substring.

Together with 639754651, it forms a pair of twin primes.

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 639754649.

It is not a weakly prime, because it can be changed into another prime (639754669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319877324 + 319877325.

It is an arithmetic number, because the mean of its divisors is an integer number (319877325).

Almost surely, 2^639754649 is an apocalyptic number.

It is an amenable number.

639754649 is a deficient number, since it is larger than the sum of its proper divisors (1).

639754649 is an equidigital number, since it uses as much as digits as its factorization.

639754649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 53.

The square root of 639754649 is about 25293.3716415981. The cubic root of 639754649 is about 861.6637384571.

The spelling of 639754649 in words is "six hundred thirty-nine million, seven hundred fifty-four thousand, six hundred forty-nine".