21210002121 has 32 divisors (see below), whose sum is σ = 35607315456. Its totient is φ = 10909080000.

The previous prime is 21210002117. The next prime is 21210002123. The reversal of 21210002121 is 12120001212.

It is not a de Polignac number, because 21210002121 - 2² = 21210002117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21210002097 and 21210002106.

It is not an unprimeable number, because it can be changed into a prime (21210002123) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 431215 + ... + 477876.

It is an arithmetic number, because the mean of its divisors is an integer number (1112728608).

Almost surely, 2^21210002121 is an apocalyptic number.

21210002121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21210002121 is a deficient number, since it is larger than the sum of its proper divisors (14397313335).

21210002121 is a wasteful number, since it uses less digits than its factorization.

21210002121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909213.

The product of its (nonzero) digits is 16, while the sum is 12.

Multiplying 21210002121 by its sum of digits (12), we get a palindrome (254520025452).

Adding to 21210002121 its reverse (12120001212), we get a palindrome (33330003333).

Subtracting from 21210002121 its reverse (12120001212), we obtain a palindrome (9090000909).

The spelling of 21210002121 in words is "twenty-one billion, two hundred ten million, two thousand, one hundred twenty-one".