21210022121 has 4 divisors (see below), whose sum is σ = 21210594132. Its totient is φ = 21209450112.

The previous prime is 21210022111. The next prime is 21210022151. The reversal of 21210022121 is 12122001212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13325470096 + 7884552025 = 115436^2 + 88795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210022121 - 2³⁴ = 4030152937 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210022096 and 21210022105.

It is not an unprimeable number, because it can be changed into a prime (21210022111) 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, 226220 + ... + 305933.

It is an arithmetic number, because the mean of its divisors is an integer number (5302648533).

Almost surely, 2^21210022121 is an apocalyptic number.

It is an amenable number.

21210022121 is a deficient number, since it is larger than the sum of its proper divisors (572011).

21210022121 is an equidigital number, since it uses as much as digits as its factorization.

21210022121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 572010.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21210022121 its reverse (12122001212), we get a palindrome (33332023333).

The spelling of 21210022121 in words is "twenty-one billion, two hundred ten million, twenty-two thousand, one hundred twenty-one".