21531333313513 has 8 divisors (see below), whose sum is σ = 21628678725000. Its totient is φ = 21434116075008.

The previous prime is 21531333313439. The next prime is 21531333313547. The reversal of 21531333313513 is 31531333313512.

It can be written as a sum of positive squares in 4 ways, for example, as 433736836569 + 21097596476944 = 658587^2 + 4593212^2 .

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 21531333313513 - 2³³ = 21522743378921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21531333313613) 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, 31706506 + ... + 32378467.

It is an arithmetic number, because the mean of its divisors is an integer number (2703584840625).

Almost surely, 2^{21531333313513} is an apocalyptic number.

It is an amenable number.

21531333313513 is a deficient number, since it is larger than the sum of its proper divisors (97345411487).

21531333313513 is a wasteful number, since it uses less digits than its factorization.

21531333313513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64086491.

The product of its digits is 109350, while the sum is 37.

Subtracting 21531333313513 from its reverse (31531333313512), we obtain a palindrome (9999999999999).

The spelling of 21531333313513 in words is "twenty-one trillion, five hundred thirty-one billion, three hundred thirty-three million, three hundred thirteen thousand, five hundred thirteen".