331000021 has 4 divisors (see below), whose sum is σ = 361090944. Its totient is φ = 300909100.

The previous prime is 331000009. The next prime is 331000037. The reversal of 331000021 is 120000133.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 331000021 - 2¹⁷ = 330868949 is a prime.

It is a super-2 number, since 2×331000021² = 219122027804000882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 330999971 and 331000007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (331000001) 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, 15045445 + ... + 15045466.

It is an arithmetic number, because the mean of its divisors is an integer number (90272736).

Almost surely, 2^331000021 is an apocalyptic number.

It is an amenable number.

331000021 is a deficient number, since it is larger than the sum of its proper divisors (30090923).

331000021 is a wasteful number, since it uses less digits than its factorization.

331000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30090922.

The product of its (nonzero) digits is 18, while the sum is 10.

The square root of 331000021 is about 18193.4059757924. The cubic root of 331000021 is about 691.7396562899.

Adding to 331000021 its reverse (120000133), we get a palindrome (451000154).

The spelling of 331000021 in words is "three hundred thirty-one million, twenty-one", and thus it is an aban number.