21030013120021 has 4 divisors (see below), whose sum is σ = 21163962248332. Its totient is φ = 20896063991712.

The previous prime is 21030013119989. The next prime is 21030013120027. The reversal of 21030013120021 is 12002131003012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7051096052100 + 13978917067921 = 2655390^2 + 3738839^2 .

It is a cyclic number.

It is not a de Polignac number, because 21030013120021 - 2⁵ = 21030013119989 is a prime.

It is a super-2 number, since 2×21030013120021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21030013119977 and 21030013120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030013120027) 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, 66974563920 + ... + 66974564233.

It is an arithmetic number, because the mean of its divisors is an integer number (5290990562083).

Almost surely, 2^{21030013120021} is an apocalyptic number.

It is an amenable number.

21030013120021 is a deficient number, since it is larger than the sum of its proper divisors (133949128311).

21030013120021 is a wasteful number, since it uses less digits than its factorization.

21030013120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133949128310.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21030013120021 its reverse (12002131003012), we get a palindrome (33032144123033).

The spelling of 21030013120021 in words is "twenty-one trillion, thirty billion, thirteen million, one hundred twenty thousand, twenty-one".