642105647 has 4 divisors (see below), whose sum is σ = 642186000. Its totient is φ = 642025296.

The previous prime is 642105643. The next prime is 642105649. The reversal of 642105647 is 746501246.

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

It is a cyclic number.

It is not a de Polignac number, because 642105647 - 2² = 642105643 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 (642105641) 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, 26678 + ... + 44675.

It is an arithmetic number, because the mean of its divisors is an integer number (160546500).

Almost surely, 2^642105647 is an apocalyptic number.

642105647 is a deficient number, since it is larger than the sum of its proper divisors (80353).

642105647 is an equidigital number, since it uses as much as digits as its factorization.

642105647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80352.

The product of its (nonzero) digits is 40320, while the sum is 35.

The square root of 642105647 is about 25339.8036101308. The cubic root of 642105647 is about 862.7179412001.

The spelling of 642105647 in words is "six hundred forty-two million, one hundred five thousand, six hundred forty-seven".