639275405209 has 9 divisors (see below), whose sum is σ = 743653410591. Its totient is φ = 547945550040.

The previous prime is 639275405191. The next prime is 639275405243. The reversal of 639275405209 is 902504572936.

The square root of 639275405209 is 799547.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 337325155209 + 301950250000 = 580797^2 + 549500^2 .

It is not a de Polignac number, because 639275405209 - 2²⁷ = 639141187481 is a prime.

It is a super-2 number, since 2×639275405209² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (639275400209) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5539719 + ... + 5653939.

Almost surely, 2^639275405209 is an apocalyptic number.

639275405209 is the 799547-th square number.

639275405209 is the 399774-th centered octagonal number.

It is an amenable number.

639275405209 is a deficient number, since it is larger than the sum of its proper divisors (104378005382).

639275405209 is an frugal number, since it uses more digits than its factorization.

639275405209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228456 (or 114228 counting only the distinct ones).

The product of its (nonzero) digits is 4082400, while the sum is 52.

It can be divided in two parts, 639275 and 405209, that added together give a square (1044484 = 1022²).

The spelling of 639275405209 in words is "six hundred thirty-nine billion, two hundred seventy-five million, four hundred five thousand, two hundred nine".