21011155549 has 2 divisors, whose sum is σ = 21011155550. Its totient is φ = 21011155548.

The previous prime is 21011155483. The next prime is 21011155619. The reversal of 21011155549 is 94555111012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12134124025 + 8877031524 = 110155^2 + 94218^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011155549 - 2⁷ = 21011155421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011125549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505577774 + 10505577775.

It is an arithmetic number, because the mean of its divisors is an integer number (10505577775).

Almost surely, 2^21011155549 is an apocalyptic number.

It is an amenable number.

21011155549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011155549 is an equidigital number, since it uses as much as digits as its factorization.

21011155549 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9000, while the sum is 34.

The spelling of 21011155549 in words is "twenty-one billion, eleven million, one hundred fifty-five thousand, five hundred forty-nine".