21234541100021 has 4 divisors (see below), whose sum is σ = 21234563084652. Its totient is φ = 21234519115392.

The previous prime is 21234541099957. The next prime is 21234541100033. The reversal of 21234541100021 is 12000114543212.

It is a happy number.

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 5694475416100 + 15540065683921 = 2386310^2 + 3942089^2 .

It is a cyclic number.

It is not a de Polignac number, because 21234541100021 - 2⁶ = 21234541099957 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 (21234541100041) 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, 9473546 + ... + 11498571.

It is an arithmetic number, because the mean of its divisors is an integer number (5308640771163).

Almost surely, 2^{21234541100021} is an apocalyptic number.

It is an amenable number.

21234541100021 is a deficient number, since it is larger than the sum of its proper divisors (21984631).

21234541100021 is a wasteful number, since it uses less digits than its factorization.

21234541100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21984630.

The product of its (nonzero) digits is 1920, while the sum is 26.

Adding to 21234541100021 its reverse (12000114543212), we get a palindrome (33234655643233).

The spelling of 21234541100021 in words is "twenty-one trillion, two hundred thirty-four billion, five hundred forty-one million, one hundred thousand, twenty-one".