663315021 has 16 divisors (see below), whose sum is σ = 1009249600. Its totient is φ = 430257744.

The previous prime is 663315017. The next prime is 663315049. The reversal of 663315021 is 120513366.

663315021 is a `hidden beast` number, since 6 + 633 + 1 + 5 + 0 + 21 = 666.

It is not a de Polignac number, because 663315021 - 2² = 663315017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663315221) 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, 330991 + ... + 332988.

It is an arithmetic number, because the mean of its divisors is an integer number (63078100).

Almost surely, 2^663315021 is an apocalyptic number.

It is an amenable number.

663315021 is a deficient number, since it is larger than the sum of its proper divisors (345934579).

663315021 is a wasteful number, since it uses less digits than its factorization.

663315021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 664025 (or 664019 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 663315021 is about 25754.9028536316. The cubic root of 663315021 is about 872.1140384236.

Adding to 663315021 its reverse (120513366), we get a palindrome (783828387).

The spelling of 663315021 in words is "six hundred sixty-three million, three hundred fifteen thousand, twenty-one".