21543317629 has 2 divisors, whose sum is σ = 21543317630. Its totient is φ = 21543317628.

The previous prime is 21543317603. The next prime is 21543317633. The reversal of 21543317629 is 92671334512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11958516025 + 9584801604 = 109355^2 + 97902^2 .

It is a cyclic number.

It is not a de Polignac number, because 21543317629 - 2⁵ = 21543317597 is a prime.

It is a super-2 number, since 2×21543317629² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21543317699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771658814 + 10771658815.

It is an arithmetic number, because the mean of its divisors is an integer number (10771658815).

Almost surely, 2^21543317629 is an apocalyptic number.

It is an amenable number.

21543317629 is a deficient number, since it is larger than the sum of its proper divisors (1).

21543317629 is an equidigital number, since it uses as much as digits as its factorization.

21543317629 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 272160, while the sum is 43.

The spelling of 21543317629 in words is "twenty-one billion, five hundred forty-three million, three hundred seventeen thousand, six hundred twenty-nine".