21003002021 has 24 divisors (see below), whose sum is σ = 23364245880. Its totient is φ = 18848479104.

The previous prime is 21003002017. The next prime is 21003002029. The reversal of 21003002021 is 12020030012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 528540100 + 20474461921 = 22990^2 + 143089^2 .

It is not a de Polignac number, because 21003002021 - 2² = 21003002017 is a prime.

It is a super-2 number, since 2×21003002021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21003001993 and 21003002011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003002029) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 535931 + ... + 573783.

It is an arithmetic number, because the mean of its divisors is an integer number (973510245).

Almost surely, 2^21003002021 is an apocalyptic number.

It is an amenable number.

21003002021 is a deficient number, since it is larger than the sum of its proper divisors (2361243859).

21003002021 is a wasteful number, since it uses less digits than its factorization.

21003002021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37973 (or 37954 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

Adding to 21003002021 its reverse (12020030012), we get a palindrome (33023032033).

The spelling of 21003002021 in words is "twenty-one billion, three million, two thousand, twenty-one".