20721004 has 12 divisors (see below), whose sum is σ = 36295000. Its totient is φ = 10351008.

The previous prime is 20720971. The next prime is 20721013. The reversal of 20721004 is 40012702.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5272 + ... + 8320.

Almost surely, 2^20721004 is an apocalyptic number.

It is an amenable number.

20721004 is a deficient number, since it is larger than the sum of its proper divisors (15573996).

20721004 is a wasteful number, since it uses less digits than its factorization.

20721004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4752 (or 4750 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 16.

The square root of 20721004 is about 4552.0329524291. The cubic root of 20721004 is about 274.6651748696.

Adding to 20721004 its reverse (40012702), we get a palindrome (60733706).

The spelling of 20721004 in words is "twenty million, seven hundred twenty-one thousand, four".