21010120121 has 4 divisors (see below), whose sum is σ = 21011203200. Its totient is φ = 21009037044.

The previous prime is 21010120111. The next prime is 21010120127. The reversal of 21010120121 is 12102101012.

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 a de Polignac number, because none of the positive numbers 2^k-21010120121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010120127) 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, 511901 + ... + 551418.

It is an arithmetic number, because the mean of its divisors is an integer number (5252800800).

Almost surely, 2^21010120121 is an apocalyptic number.

It is an amenable number.

21010120121 is a deficient number, since it is larger than the sum of its proper divisors (1083079).

21010120121 is a wasteful number, since it uses less digits than its factorization.

21010120121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1083078.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21010120121 its reverse (12102101012), we get a palindrome (33112221133).

The spelling of 21010120121 in words is "twenty-one billion, ten million, one hundred twenty thousand, one hundred twenty-one".