2165721533 has 2 divisors, whose sum is σ = 2165721534. Its totient is φ = 2165721532.

The previous prime is 2165721497. The next prime is 2165721539. The reversal of 2165721533 is 3351275612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1283215684 + 882505849 = 35822^2 + 29707^2 .

It is a cyclic number.

It is not a de Polignac number, because 2165721533 - 2¹⁰ = 2165720509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2165721493 and 2165721502.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2165721539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1082860766 + 1082860767.

It is an arithmetic number, because the mean of its divisors is an integer number (1082860767).

Almost surely, 2^2165721533 is an apocalyptic number.

It is an amenable number.

2165721533 is a deficient number, since it is larger than the sum of its proper divisors (1).

2165721533 is an equidigital number, since it uses as much as digits as its factorization.

2165721533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37800, while the sum is 35.

The square root of 2165721533 is about 46537.3133410170. The cubic root of 2165721533 is about 1293.8011659912.

The spelling of 2165721533 in words is "two billion, one hundred sixty-five million, seven hundred twenty-one thousand, five hundred thirty-three".