21213213021 has 96 divisors (see below), whose sum is σ = 41219942400. Its totient is φ = 10152604800.

The previous prime is 21213213019. The next prime is 21213213023. The reversal of 21213213021 is 12031231212.

21213213021 is a `hidden beast` number, since 21 + 21 + 321 + 302 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (21213213019) and next prime (21213213023).

It is not a de Polignac number, because 21213213021 - 2¹ = 21213213019 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21213212985 and 21213213003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213213023) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 5394426 + ... + 5398356.

It is an arithmetic number, because the mean of its divisors is an integer number (429374400).

Almost surely, 2^21213213021 is an apocalyptic number.

21213213021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21213213021 is a deficient number, since it is larger than the sum of its proper divisors (20006729379).

21213213021 is a wasteful number, since it uses less digits than its factorization.

21213213021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4567 (or 4564 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21213213021 its reverse (12031231212), we get a palindrome (33244444233).

The spelling of 21213213021 in words is "twenty-one billion, two hundred thirteen million, two hundred thirteen thousand, twenty-one".