21003006 has 32 divisors (see below), whose sum is σ = 43388928. Its totient is φ = 6773760.

The previous prime is 21003001. The next prime is 21003011. The reversal of 21003006 is 60030012.

It is an interprime number because it is at equal distance from previous prime (21003001) and next prime (21003011).

It is a super-2 number, since 2×21003006² = 882252522072072, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21002982 and 21003000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003001) 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, 32446 + ... + 33086.

It is an arithmetic number, because the mean of its divisors is an integer number (1355904).

Almost surely, 2^21003006 is an apocalyptic number.

21003006 is an abundant number, since it is smaller than the sum of its proper divisors (22385922).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21003006 is a wasteful number, since it uses less digits than its factorization.

21003006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21003006 is about 4582.9036647087. The cubic root of 21003006 is about 275.9055810197.

Adding to 21003006 its reverse (60030012), we get a palindrome (81033018).

The spelling of 21003006 in words is "twenty-one million, three thousand, six".