21020021003 has 4 divisors (see below), whose sum is σ = 21021624360. Its totient is φ = 21018417648.

The previous prime is 21020020997. The next prime is 21020021017. The reversal of 21020021003 is 30012002012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21020021003 - 2¹⁴ = 21020004619 is a prime.

It is a super-2 number, since 2×21020021003² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020021023) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 781850 + ... + 808287.

It is an arithmetic number, because the mean of its divisors is an integer number (5255406090).

Almost surely, 2^21020021003 is an apocalyptic number.

21020021003 is a deficient number, since it is larger than the sum of its proper divisors (1603357).

21020021003 is a wasteful number, since it uses less digits than its factorization.

21020021003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1603356.

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

Adding to 21020021003 its reverse (30012002012), we get a palindrome (51032023015).

The spelling of 21020021003 in words is "twenty-one billion, twenty million, twenty-one thousand, three".