21121020121 has 8 divisors (see below), whose sum is σ = 21168886464. Its totient is φ = 21073209360.

The previous prime is 21121020113. The next prime is 21121020127. The reversal of 21121020121 is 12102012112.

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 21121020121 - 2³ = 21121020113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121020127) 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, 799951 + ... + 825931.

It is an arithmetic number, because the mean of its divisors is an integer number (2646110808).

Almost surely, 2^21121020121 is an apocalyptic number.

It is an amenable number.

21121020121 is a deficient number, since it is larger than the sum of its proper divisors (47866343).

21121020121 is an equidigital number, since it uses as much as digits as its factorization.

21121020121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27791.

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

Adding to 21121020121 its reverse (12102012112), we get a palindrome (33223032233).

The spelling of 21121020121 in words is "twenty-one billion, one hundred twenty-one million, twenty thousand, one hundred twenty-one".