21012111121 has 8 divisors (see below), whose sum is σ = 21507115520. Its totient is φ = 20517395472.

The previous prime is 21012111097. The next prime is 21012111149. The reversal of 21012111121 is 12111121012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21012111121 - 2⁵ = 21012111089 is a prime.

It is a super-2 number, since 2×21012111121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012111151) 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, 78736 + ... + 219598.

It is an arithmetic number, because the mean of its divisors is an integer number (2688389440).

Almost surely, 2^21012111121 is an apocalyptic number.

It is an amenable number.

21012111121 is a deficient number, since it is larger than the sum of its proper divisors (495004399).

21012111121 is a wasteful number, since it uses less digits than its factorization.

21012111121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144375.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21012111121 its reverse (12111121012), we get a palindrome (33123232133).

The spelling of 21012111121 in words is "twenty-one billion, twelve million, one hundred eleven thousand, one hundred twenty-one".