639138212 has 6 divisors (see below), whose sum is σ = 1118491878. Its totient is φ = 319569104.

The previous prime is 639138211. The next prime is 639138233. The reversal of 639138212 is 212831936.

It can be written as a sum of positive squares in only one way, i.e., 342472036 + 296666176 = 18506^2 + 17224^2 .

It is not an unprimeable number, because it can be changed into a prime (639138211) 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, 79892273 + ... + 79892280.

It is an arithmetic number, because the mean of its divisors is an integer number (186415313).

Almost surely, 2^639138212 is an apocalyptic number.

It is an amenable number.

639138212 is a deficient number, since it is larger than the sum of its proper divisors (479353666).

639138212 is a wasteful number, since it uses less digits than its factorization.

639138212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159784557 (or 159784555 counting only the distinct ones).

The product of its digits is 15552, while the sum is 35.

The square root of 639138212 is about 25281.1829628283. The cubic root of 639138212 is about 861.3868968571.

The spelling of 639138212 in words is "six hundred thirty-nine million, one hundred thirty-eight thousand, two hundred twelve".