21531235450213 has 4 divisors (see below), whose sum is σ = 21540440769120. Its totient is φ = 21522030131308.

The previous prime is 21531235450199. The next prime is 21531235450321. The reversal of 21531235450213 is 31205453213512.

It is a happy number.

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 21531235450213 - 2²⁹ = 21530698579301 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 (21531235490213) 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, 4602655945 + ... + 4602660622.

It is an arithmetic number, because the mean of its divisors is an integer number (5385110192280).

Almost surely, 2^{21531235450213} is an apocalyptic number.

It is an amenable number.

21531235450213 is a deficient number, since it is larger than the sum of its proper divisors (9205318907).

21531235450213 is an equidigital number, since it uses as much as digits as its factorization.

21531235450213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9205318906.

The product of its (nonzero) digits is 108000, while the sum is 37.

Adding to 21531235450213 its reverse (31205453213512), we get a palindrome (52736688663725).

The spelling of 21531235450213 in words is "twenty-one trillion, five hundred thirty-one billion, two hundred thirty-five million, four hundred fifty thousand, two hundred thirteen".