21031331021 has 16 divisors (see below), whose sum is σ = 22485043200. Its totient is φ = 19612734768.

The previous prime is 21031331017. The next prime is 21031331047. The reversal of 21031331021 is 12013313012.

It is a cyclic number.

It is not a de Polignac number, because 21031331021 - 2² = 21031331017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031331221) 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, 2004836 + ... + 2015298.

It is an arithmetic number, because the mean of its divisors is an integer number (1405315200).

Almost surely, 2^21031331021 is an apocalyptic number.

It is an amenable number.

21031331021 is a deficient number, since it is larger than the sum of its proper divisors (1453712179).

21031331021 is a wasteful number, since it uses less digits than its factorization.

21031331021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12128.

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

Adding to 21031331021 its reverse (12013313012), we get a palindrome (33044644033).

The spelling of 21031331021 in words is "twenty-one billion, thirty-one million, three hundred thirty-one thousand, twenty-one".