21555304189 has 2 divisors, whose sum is σ = 21555304190. Its totient is φ = 21555304188.

The previous prime is 21555304157. The next prime is 21555304213. The reversal of 21555304189 is 98140355512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21482764900 + 72539289 = 146570^2 + 8517^2 .

It is a cyclic number.

It is not a de Polignac number, because 21555304189 - 2⁵ = 21555304157 is a prime.

It is a super-2 number, since 2×21555304189² (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 (21555304109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777652094 + 10777652095.

It is an arithmetic number, because the mean of its divisors is an integer number (10777652095).

Almost surely, 2^21555304189 is an apocalyptic number.

It is an amenable number.

21555304189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21555304189 is an equidigital number, since it uses as much as digits as its factorization.

21555304189 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216000, while the sum is 43.

The spelling of 21555304189 in words is "twenty-one billion, five hundred fifty-five million, three hundred four thousand, one hundred eighty-nine".