21121020013 has 4 divisors (see below), whose sum is σ = 21125246688. Its totient is φ = 21116793340.

The previous prime is 21121020001. The next prime is 21121020029. The reversal of 21121020013 is 31002012112.

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 not a de Polignac number, because 21121020013 - 2³³ = 12531085421 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121019975 and 21121020002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121020113) 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, 2105833 + ... + 2115838.

It is an arithmetic number, because the mean of its divisors is an integer number (5281311672).

Almost surely, 2^21121020013 is an apocalyptic number.

It is an amenable number.

21121020013 is a deficient number, since it is larger than the sum of its proper divisors (4226675).

21121020013 is an equidigital number, since it uses as much as digits as its factorization.

21121020013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4226674.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21121020013 its reverse (31002012112), we get a palindrome (52123032125).

The spelling of 21121020013 in words is "twenty-one billion, one hundred twenty-one million, twenty thousand, thirteen".