642647 has 4 divisors (see below), whose sum is σ = 645216. Its totient is φ = 640080.

The previous prime is 642623. The next prime is 642673. The reversal of 642647 is 746246.

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 642647 - 2¹⁰ = 641623 is a prime.

It is a d-powerful number, because it can be written as 6⁷ + 4⁷ + 6⁷ + 2⁹ + 4⁸ + 7³ .

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 642647.

It is not an unprimeable number, because it can be changed into a prime (642247) 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, 863 + ... + 1424.

It is an arithmetic number, because the mean of its divisors is an integer number (161304).

2⁶⁴²⁶⁴⁷ is an apocalyptic number.

642647 is a deficient number, since it is larger than the sum of its proper divisors (2569).

642647 is a wasteful number, since it uses less digits than its factorization.

642647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2568.

The product of its digits is 8064, while the sum is 29.

The square root of 642647 is about 801.6526679304. The cubic root of 642647 is about 86.2960322787.

The spelling of 642647 in words is "six hundred forty-two thousand, six hundred forty-seven".