642731 has 8 divisors (see below), whose sum is σ = 668304. Its totient is φ = 617760.

The previous prime is 642701. The next prime is 642737. The reversal of 642731 is 137246.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642731 - 2¹⁴ = 626347 is a prime.

It is a super-2 number, since 2×642731² = 826206276722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642697 and 642706.

It is not an unprimeable number, because it can be changed into a prime (642737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3461 + ... + 3641.

It is an arithmetic number, because the mean of its divisors is an integer number (83538).

2⁶⁴²⁷³¹ is an apocalyptic number.

642731 is a deficient number, since it is larger than the sum of its proper divisors (25573).

642731 is a wasteful number, since it uses less digits than its factorization.

642731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301.

The product of its digits is 1008, while the sum is 23.

The square root of 642731 is about 801.7050579858. The cubic root of 642731 is about 86.2997920155.

Adding to 642731 its reverse (137246), we get a palindrome (779977).

The spelling of 642731 in words is "six hundred forty-two thousand, seven hundred thirty-one".