21730632817 has 2 divisors, whose sum is σ = 21730632818. Its totient is φ = 21730632816.

The previous prime is 21730632787. The next prime is 21730632907. The reversal of 21730632817 is 71823603712.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21644588641 + 86044176 = 147121^2 + 9276^2 .

It is a cyclic number.

It is not a de Polignac number, because 21730632817 - 2¹⁹ = 21730108529 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21730632817.

It is not a weakly prime, because it can be changed into another prime (21730632317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865316408 + 10865316409.

It is an arithmetic number, because the mean of its divisors is an integer number (10865316409).

Almost surely, 2^21730632817 is an apocalyptic number.

It is an amenable number.

21730632817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21730632817 is an equidigital number, since it uses as much as digits as its factorization.

21730632817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84672, while the sum is 40.

The spelling of 21730632817 in words is "twenty-one billion, seven hundred thirty million, six hundred thirty-two thousand, eight hundred seventeen".