663842 has 4 divisors (see below), whose sum is σ = 995766. Its totient is φ = 331920.

The previous prime is 663827. The next prime is 663853. The reversal of 663842 is 248366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 248366 = 2 ⋅124183.

It can be written as a sum of positive squares in only one way, i.e., 373321 + 290521 = 611^2 + 539^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165959 + ... + 165962.

2⁶⁶³⁸⁴² is an apocalyptic number.

663842 is a deficient number, since it is larger than the sum of its proper divisors (331924).

663842 is a wasteful number, since it uses less digits than its factorization.

663842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331923.

The product of its digits is 6912, while the sum is 29.

The square root of 663842 is about 814.7649967936. The cubic root of 663842 is about 87.2344931295.

The spelling of 663842 in words is "six hundred sixty-three thousand, eight hundred forty-two".