21716421165073 has 4 divisors (see below), whose sum is σ = 21754057944100. Its totient is φ = 21678784386048.

The previous prime is 21716421165017. The next prime is 21716421165107. The reversal of 21716421165073 is 37056112461712.

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 13925495329344 + 7790925835729 = 3731688^2 + 2791223^2 .

It is a cyclic number.

It is not a de Polignac number, because 21716421165073 - 2²¹ = 21716419067921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21716421165973) 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, 18818388648 + ... + 18818389801.

It is an arithmetic number, because the mean of its divisors is an integer number (5438514486025).

Almost surely, 2^{21716421165073} is an apocalyptic number.

It is an amenable number.

21716421165073 is a deficient number, since it is larger than the sum of its proper divisors (37636779027).

21716421165073 is an equidigital number, since it uses as much as digits as its factorization.

21716421165073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37636779026.

The product of its (nonzero) digits is 423360, while the sum is 46.

The spelling of 21716421165073 in words is "twenty-one trillion, seven hundred sixteen billion, four hundred twenty-one million, one hundred sixty-five thousand, seventy-three".