21003121331 has 4 divisors (see below), whose sum is σ = 21030721464. Its totient is φ = 20975521200.

The previous prime is 21003121289. The next prime is 21003121357. The reversal of 21003121331 is 13312130012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21003121331 is a prime.

It is a super-2 number, since 2×21003121331² (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 (21003141331) 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, 13798925 + ... + 13800446.

It is an arithmetic number, because the mean of its divisors is an integer number (5257680366).

Almost surely, 2^21003121331 is an apocalyptic number.

21003121331 is a deficient number, since it is larger than the sum of its proper divisors (27600133).

21003121331 is an equidigital number, since it uses as much as digits as its factorization.

21003121331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27600132.

The product of its (nonzero) digits is 108, while the sum is 17.

Adding to 21003121331 its reverse (13312130012), we get a palindrome (34315251343).

The spelling of 21003121331 in words is "twenty-one billion, three million, one hundred twenty-one thousand, three hundred thirty-one".