663121 has 4 divisors (see below), whose sum is σ = 684544. Its totient is φ = 641700.

The previous prime is 663097. The next prime is 663127. The reversal of 663121 is 121366.

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 not a de Polignac number, because 663121 - 2¹⁵ = 630353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (663127) 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, 10665 + ... + 10726.

It is an arithmetic number, because the mean of its divisors is an integer number (171136).

2⁶⁶³¹²¹ is an apocalyptic number.

It is an amenable number.

663121 is a deficient number, since it is larger than the sum of its proper divisors (21423).

663121 is a wasteful number, since it uses less digits than its factorization.

663121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21422.

The product of its digits is 216, while the sum is 19.

The square root of 663121 is about 814.3224177192. The cubic root of 663121 is about 87.2028998418.

Adding to 663121 its reverse (121366), we get a palindrome (784487).

It can be divided in two parts, 663 and 121, that added together give a square (784 = 28²).

The spelling of 663121 in words is "six hundred sixty-three thousand, one hundred twenty-one".