21555251089 has 2 divisors, whose sum is σ = 21555251090. Its totient is φ = 21555251088.

The previous prime is 21555251017. The next prime is 21555251129. The reversal of 21555251089 is 98015255512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21555231489 + 19600 = 146817^2 + 140^2 .

It is a cyclic number.

It is not a de Polignac number, because 21555251089 - 2¹⁷ = 21555120017 is a prime.

It is not a weakly prime, because it can be changed into another prime (21555251489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777625544 + 10777625545.

It is an arithmetic number, because the mean of its divisors is an integer number (10777625545).

Almost surely, 2^21555251089 is an apocalyptic number.

It is an amenable number.

21555251089 is a deficient number, since it is larger than the sum of its proper divisors (1).

21555251089 is an equidigital number, since it uses as much as digits as its factorization.

21555251089 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180000, while the sum is 43.

The spelling of 21555251089 in words is "twenty-one billion, five hundred fifty-five million, two hundred fifty-one thousand, eighty-nine".