21002010121 has 4 divisors (see below), whose sum is σ = 21021052032. Its totient is φ = 20982968212.

The previous prime is 21002010059. The next prime is 21002010131. The reversal of 21002010121 is 12101020012.

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-21002010121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21002010098 and 21002010107.

It is not an unprimeable number, because it can be changed into a prime (21002010131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9519301 + ... + 9521506.

It is an arithmetic number, because the mean of its divisors is an integer number (5255263008).

Almost surely, 2^21002010121 is an apocalyptic number.

It is an amenable number.

21002010121 is a deficient number, since it is larger than the sum of its proper divisors (19041911).

21002010121 is a wasteful number, since it uses less digits than its factorization.

21002010121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19041910.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21002010121 its reverse (12101020012), we get a palindrome (33103030133).

The spelling of 21002010121 in words is "twenty-one billion, two million, ten thousand, one hundred twenty-one".