21031000221 has 16 divisors (see below), whose sum is σ = 34960624128. Its totient is φ = 10925194800.

The previous prime is 21031000219. The next prime is 21031000223. The reversal of 21031000221 is 12200013012.

It is an interprime number because it is at equal distance from previous prime (21031000219) and next prime (21031000223).

It is not a de Polignac number, because 21031000221 - 2¹ = 21031000219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21031000197 and 21031000206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031000223) 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, 45521415 + ... + 45521876.

It is an arithmetic number, because the mean of its divisors is an integer number (2185039008).

Almost surely, 2^21031000221 is an apocalyptic number.

21031000221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21031000221 is a deficient number, since it is larger than the sum of its proper divisors (13929623907).

21031000221 is a wasteful number, since it uses less digits than its factorization.

21031000221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91043312.

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21031000221 its reverse (12200013012), we get a palindrome (33231013233).

The spelling of 21031000221 in words is "twenty-one billion, thirty-one million, two hundred twenty-one", and thus it is an aban number.