642055709 has 4 divisors (see below), whose sum is σ = 659408604. Its totient is φ = 624702816.

The previous prime is 642055703. The next prime is 642055721. The reversal of 642055709 is 907550246.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 427579684 + 214476025 = 20678^2 + 14645^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642055709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642055703) 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, 8676392 + ... + 8676465.

It is an arithmetic number, because the mean of its divisors is an integer number (164852151).

Almost surely, 2^642055709 is an apocalyptic number.

It is an amenable number.

642055709 is a deficient number, since it is larger than the sum of its proper divisors (17352895).

642055709 is a wasteful number, since it uses less digits than its factorization.

642055709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17352894.

The product of its (nonzero) digits is 75600, while the sum is 38.

The square root of 642055709 is about 25338.8182242187. The cubic root of 642055709 is about 862.6955754489.

The spelling of 642055709 in words is "six hundred forty-two million, fifty-five thousand, seven hundred nine".