663245921 has 16 divisors (see below), whose sum is σ = 740418000. Its totient is φ = 589897728.

The previous prime is 663245911. The next prime is 663245923. The reversal of 663245921 is 129542366.

It can be written as a sum of positive squares in 8 ways, for example, as 2190400 + 661055521 = 1480^2 + 25711^2 .

It is a cyclic number.

It is not a de Polignac number, because 663245921 - 2¹⁴ = 663229537 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (663245923) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 216005 + ... + 219053.

It is an arithmetic number, because the mean of its divisors is an integer number (46276125).

Almost surely, 2^663245921 is an apocalyptic number.

It is an amenable number.

663245921 is a deficient number, since it is larger than the sum of its proper divisors (77172079).

663245921 is a wasteful number, since it uses less digits than its factorization.

663245921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3668.

The product of its digits is 77760, while the sum is 38.

The square root of 663245921 is about 25753.5613265428. The cubic root of 663245921 is about 872.0837535811.

The spelling of 663245921 in words is "six hundred sixty-three million, two hundred forty-five thousand, nine hundred twenty-one".