21221002121 has 4 divisors (see below), whose sum is σ = 23150184144. Its totient is φ = 19291820100.

The previous prime is 21221002109. The next prime is 21221002133. The reversal of 21221002121 is 12120012212.

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 an interprime number because it is at equal distance from previous prime (21221002109) and next prime (21221002133).

It is a cyclic number.

It is not a de Polignac number, because 21221002121 - 2¹⁰ = 21221001097 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221002096 and 21221002105.

It is not an unprimeable number, because it can be changed into a prime (21221002721) 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 3 ways as a sum of consecutive naturals, for example, 964590995 + ... + 964591016.

It is an arithmetic number, because the mean of its divisors is an integer number (5787546036).

Almost surely, 2^21221002121 is an apocalyptic number.

It is an amenable number.

21221002121 is a deficient number, since it is larger than the sum of its proper divisors (1929182023).

21221002121 is a wasteful number, since it uses less digits than its factorization.

21221002121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1929182022.

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

Adding to 21221002121 its reverse (12120012212), we get a palindrome (33341014333).

The spelling of 21221002121 in words is "twenty-one billion, two hundred twenty-one million, two thousand, one hundred twenty-one".