663621 has 8 divisors (see below), whose sum is σ = 1011264. Its totient is φ = 379200.

The previous prime is 663601. The next prime is 663631. The reversal of 663621 is 126366.

663621 is nontrivially palindromic in base 2.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 663621 - 2⁵ = 663589 is a prime.

It is an Ulam number.

663621 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 663591 and 663600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15780 + ... + 15821.

It is an arithmetic number, because the mean of its divisors is an integer number (126408).

2⁶⁶³⁶²¹ is an apocalyptic number.

It is an amenable number.

663621 is a deficient number, since it is larger than the sum of its proper divisors (347643).

663621 is a wasteful number, since it uses less digits than its factorization.

663621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31611.

The product of its digits is 1296, while the sum is 24.

The square root of 663621 is about 814.6293635759. The cubic root of 663621 is about 87.2248116276.

Adding to 663621 its reverse (126366), we get a palindrome (789987).

The spelling of 663621 in words is "six hundred sixty-three thousand, six hundred twenty-one".