21221212202121 has 8 divisors (see below), whose sum is σ = 29059677970624. Its totient is φ = 13765110617520.

The previous prime is 21221212202089. The next prime is 21221212202129. The reversal of 21221212202121 is 12120221212212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21221212202121 - 2⁵ = 21221212202089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221212202129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95591045845 + ... + 95591046066.

It is an arithmetic number, because the mean of its divisors is an integer number (3632459746328).

Almost surely, 2^{21221212202121} is an apocalyptic number.

It is an amenable number.

21221212202121 is a deficient number, since it is larger than the sum of its proper divisors (7838465768503).

21221212202121 is a wasteful number, since it uses less digits than its factorization.

21221212202121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191182091951.

The product of its (nonzero) digits is 256, while the sum is 21.

Adding to 21221212202121 its reverse (12120221212212), we get a palindrome (33341433414333).

The spelling of 21221212202121 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twelve million, two hundred two thousand, one hundred twenty-one".