21212002021 has 16 divisors (see below), whose sum is σ = 25524172800. Its totient is φ = 17220750768.

The previous prime is 21212002013. The next prime is 21212002027. The reversal of 21212002021 is 12020021212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21212002021 - 2³ = 21212002013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21212001992 and 21212002010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212002027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 638016 + ... + 670438.

It is an arithmetic number, because the mean of its divisors is an integer number (1595260800).

Almost surely, 2^21212002021 is an apocalyptic number.

It is an amenable number.

21212002021 is a deficient number, since it is larger than the sum of its proper divisors (4312170779).

21212002021 is a wasteful number, since it uses less digits than its factorization.

21212002021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37368.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21212002021 its reverse (12020021212), we get a palindrome (33232023233).

The spelling of 21212002021 in words is "twenty-one billion, two hundred twelve million, two thousand, twenty-one".