663851 has 4 divisors (see below), whose sum is σ = 671400. Its totient is φ = 656304.

The previous prime is 663827. The next prime is 663853. The reversal of 663851 is 158366.

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 663851 - 2⁶ = 663787 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (663853) 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, 3641 + ... + 3818.

It is an arithmetic number, because the mean of its divisors is an integer number (167850).

2⁶⁶³⁸⁵¹ is an apocalyptic number.

663851 is a deficient number, since it is larger than the sum of its proper divisors (7549).

663851 is an equidigital number, since it uses as much as digits as its factorization.

663851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7548.

The product of its digits is 4320, while the sum is 29.

The square root of 663851 is about 814.7705198398. The cubic root of 663851 is about 87.2348873533.

The spelling of 663851 in words is "six hundred sixty-three thousand, eight hundred fifty-one".