21436516973 has 2 divisors, whose sum is σ = 21436516974. Its totient is φ = 21436516972.

The previous prime is 21436516967. The next prime is 21436517059. The reversal of 21436516973 is 37961563412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11642841604 + 9793675369 = 107902^2 + 98963^2 .

It is a cyclic number.

It is not a de Polignac number, because 21436516973 - 2¹⁰ = 21436515949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21436516963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10718258486 + 10718258487.

It is an arithmetic number, because the mean of its divisors is an integer number (10718258487).

Almost surely, 2^21436516973 is an apocalyptic number.

It is an amenable number.

21436516973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21436516973 is an equidigital number, since it uses as much as digits as its factorization.

21436516973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 816480, while the sum is 47.

The spelling of 21436516973 in words is "twenty-one billion, four hundred thirty-six million, five hundred sixteen thousand, nine hundred seventy-three".