639863547 has 4 divisors (see below), whose sum is σ = 853151400. Its totient is φ = 426575696.

The previous prime is 639863491. The next prime is 639863563. The reversal of 639863547 is 745368936.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-639863547 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639863547.

It is not an unprimeable number, because it can be changed into a prime (639863597) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106643922 + ... + 106643927.

It is an arithmetic number, because the mean of its divisors is an integer number (213287850).

Almost surely, 2^639863547 is an apocalyptic number.

639863547 is a deficient number, since it is larger than the sum of its proper divisors (213287853).

639863547 is a wasteful number, since it uses less digits than its factorization.

639863547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213287852.

The product of its digits is 3265920, while the sum is 51.

The square root of 639863547 is about 25295.5242483725. The cubic root of 639863547 is about 861.7126260186.

The spelling of 639863547 in words is "six hundred thirty-nine million, eight hundred sixty-three thousand, five hundred forty-seven".