21213545145421 has 8 divisors (see below), whose sum is σ = 21216430703160. Its totient is φ = 21210659785728.

The previous prime is 21213545145409. The next prime is 21213545145433. The reversal of 21213545145421 is 12454154531212.

It is an interprime number because it is at equal distance from previous prime (21213545145409) and next prime (21213545145433).

It can be written as a sum of positive squares in 4 ways, for example, as 8800316100 + 21204744829321 = 93810^2 + 4604861^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21213545145421 - 2²⁵ = 21213511590989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213545145451) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 434528005 + ... + 434576821.

It is an arithmetic number, because the mean of its divisors is an integer number (2652053837895).

Almost surely, 2^{21213545145421} is an apocalyptic number.

It is an amenable number.

21213545145421 is a deficient number, since it is larger than the sum of its proper divisors (2885557739).

21213545145421 is a wasteful number, since it uses less digits than its factorization.

21213545145421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99023.

The product of its digits is 192000, while the sum is 40.

Adding to 21213545145421 its reverse (12454154531212), we get a palindrome (33667699676633).

The spelling of 21213545145421 in words is "twenty-one trillion, two hundred thirteen billion, five hundred forty-five million, one hundred forty-five thousand, four hundred twenty-one".