639746217 has 48 divisors (see below), whose sum is σ = 1047391488. Its totient is φ = 372889440.

The previous prime is 639746213. The next prime is 639746267. The reversal of 639746217 is 712647936.

639746217 is a `hidden beast` number, since 6 + 397 + 46 + 217 = 666.

It is not a de Polignac number, because 639746217 - 2² = 639746213 is a prime.

It is a super-2 number, since 2×639746217² = 818550444331622178, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (639746213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 284098 + ... + 286340.

It is an arithmetic number, because the mean of its divisors is an integer number (21820656).

Almost surely, 2^639746217 is an apocalyptic number.

639746217 is a gapful number since it is divisible by the number (67) formed by its first and last digit.

It is an amenable number.

639746217 is a deficient number, since it is larger than the sum of its proper divisors (407645271).

639746217 is a wasteful number, since it uses less digits than its factorization.

639746217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2370 (or 2367 counting only the distinct ones).

The product of its digits is 381024, while the sum is 45.

The square root of 639746217 is about 25293.2049570631. The cubic root of 639746217 is about 861.6599528493.

The spelling of 639746217 in words is "six hundred thirty-nine million, seven hundred forty-six thousand, two hundred seventeen".