21002120003 has 4 divisors (see below), whose sum is σ = 22107494760. Its totient is φ = 19896745248.

The previous prime is 21002119987. The next prime is 21002120081. The reversal of 21002120003 is 30002120012.

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 21002120003 - 2⁴ = 21002119987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21002120903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 552687350 + ... + 552687387.

It is an arithmetic number, because the mean of its divisors is an integer number (5526873690).

Almost surely, 2^21002120003 is an apocalyptic number.

21002120003 is a deficient number, since it is larger than the sum of its proper divisors (1105374757).

21002120003 is a wasteful number, since it uses less digits than its factorization.

21002120003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105374756.

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

Adding to 21002120003 its reverse (30002120012), we get a palindrome (51004240015).

Subtracting 21002120003 from its reverse (30002120012), we obtain a palindrome (9000000009).

The spelling of 21002120003 in words is "twenty-one billion, two million, one hundred twenty thousand, three".