21217068813 has 4 divisors (see below), whose sum is σ = 28289425088. Its totient is φ = 14144712540.

The previous prime is 21217068811. The next prime is 21217068833. The reversal of 21217068813 is 31886071212.

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 not a de Polignac number, because 21217068813 - 2¹ = 21217068811 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 (21217068811) 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, 3536178133 + ... + 3536178138.

It is an arithmetic number, because the mean of its divisors is an integer number (7072356272).

Almost surely, 2^21217068813 is an apocalyptic number.

It is an amenable number.

21217068813 is a deficient number, since it is larger than the sum of its proper divisors (7072356275).

21217068813 is an equidigital number, since it uses as much as digits as its factorization.

21217068813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7072356274.

The product of its (nonzero) digits is 32256, while the sum is 39.

The spelling of 21217068813 in words is "twenty-one billion, two hundred seventeen million, sixty-eight thousand, eight hundred thirteen".