21751664533 has 2 divisors, whose sum is σ = 21751664534. Its totient is φ = 21751664532.

The previous prime is 21751664497. The next prime is 21751664573. The reversal of 21751664533 is 33546615712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21392865169 + 358799364 = 146263^2 + 18942^2 .

It is a cyclic number.

It is not a de Polignac number, because 21751664533 - 2¹³ = 21751656341 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21751664533.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21751664573) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10875832266 + 10875832267.

It is an arithmetic number, because the mean of its divisors is an integer number (10875832267).

Almost surely, 2^21751664533 is an apocalyptic number.

It is an amenable number.

21751664533 is a deficient number, since it is larger than the sum of its proper divisors (1).

21751664533 is an equidigital number, since it uses as much as digits as its factorization.

21751664533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 453600, while the sum is 43.

The spelling of 21751664533 in words is "twenty-one billion, seven hundred fifty-one million, six hundred sixty-four thousand, five hundred thirty-three".