21210021121 has 4 divisors (see below), whose sum is σ = 21321068544. Its totient is φ = 21098973700.

The previous prime is 21210021103. The next prime is 21210021137. The reversal of 21210021121 is 12112001212.

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 a cyclic number.

It is not a de Polignac number, because 21210021121 - 2³³ = 12620086529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210621121) 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, 55523425 + ... + 55523806.

It is an arithmetic number, because the mean of its divisors is an integer number (5330267136).

Almost surely, 2^21210021121 is an apocalyptic number.

It is an amenable number.

21210021121 is a deficient number, since it is larger than the sum of its proper divisors (111047423).

21210021121 is a wasteful number, since it uses less digits than its factorization.

21210021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111047422.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21210021121 its reverse (12112001212), we get a palindrome (33322022333).

The spelling of 21210021121 in words is "twenty-one billion, two hundred ten million, twenty-one thousand, one hundred twenty-one".