642761 has 4 divisors (see below), whose sum is σ = 734592. Its totient is φ = 550932.

The previous prime is 642739. The next prime is 642769. The reversal of 642761 is 167246.

642761 is nontrivially palindromic in base 16.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 642761 - 2¹⁴ = 626377 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642761.

It is not an unprimeable number, because it can be changed into a prime (642769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45905 + ... + 45918.

It is an arithmetic number, because the mean of its divisors is an integer number (183648).

2⁶⁴²⁷⁶¹ is an apocalyptic number.

It is an amenable number.

642761 is a deficient number, since it is larger than the sum of its proper divisors (91831).

642761 is an equidigital number, since it uses as much as digits as its factorization.

642761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91830.

The product of its digits is 2016, while the sum is 26.

The square root of 642761 is about 801.7237678902. The cubic root of 642761 is about 86.3011346993.

The spelling of 642761 in words is "six hundred forty-two thousand, seven hundred sixty-one".