642688 has 16 divisors (see below), whose sum is σ = 1280610. Its totient is φ = 321280.

The previous prime is 642683. The next prime is 642701. The reversal of 642688 is 886246.

It can be written as a sum of positive squares in only one way, i.e., 419904 + 222784 = 648^2 + 472^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is not an unprimeable number, because it can be changed into a prime (642683) by changing a digit.

642688 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2383 + ... + 2638.

2⁶⁴²⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

642688 is a deficient number, since it is larger than the sum of its proper divisors (637922).

642688 is an equidigital number, since it uses as much as digits as its factorization.

642688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5035 (or 5023 counting only the distinct ones).

The product of its digits is 18432, while the sum is 34.

The square root of 642688 is about 801.6782396947. The cubic root of 642688 is about 86.2978674293.

The spelling of 642688 in words is "six hundred forty-two thousand, six hundred eighty-eight".