21000121013 has 4 divisors (see below), whose sum is σ = 22105390560. Its totient is φ = 19894851468.

The previous prime is 21000120971. The next prime is 21000121031. The reversal of 21000121013 is 31012100012.

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-21000121013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000120985 and 21000121003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000121073) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 552634745 + ... + 552634782.

It is an arithmetic number, because the mean of its divisors is an integer number (5526347640).

Almost surely, 2^21000121013 is an apocalyptic number.

It is an amenable number.

21000121013 is a deficient number, since it is larger than the sum of its proper divisors (1105269547).

21000121013 is a wasteful number, since it uses less digits than its factorization.

21000121013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105269546.

The product of its (nonzero) digits is 12, while the sum is 11.

Adding to 21000121013 its reverse (31012100012), we get a palindrome (52012221025).

The spelling of 21000121013 in words is "twenty-one billion, one hundred twenty-one thousand, thirteen".