21151051549 has 2 divisors, whose sum is σ = 21151051550. Its totient is φ = 21151051548.

The previous prime is 21151051543. The next prime is 21151051627. The reversal of 21151051549 is 94515015112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20404122649 + 746928900 = 142843^2 + 27330^2 .

It is a cyclic number.

It is not a de Polignac number, because 21151051549 - 2⁷ = 21151051421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21151051543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10575525774 + 10575525775.

It is an arithmetic number, because the mean of its divisors is an integer number (10575525775).

Almost surely, 2^21151051549 is an apocalyptic number.

It is an amenable number.

21151051549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21151051549 is an equidigital number, since it uses as much as digits as its factorization.

21151051549 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 21151051549 in words is "twenty-one billion, one hundred fifty-one million, fifty-one thousand, five hundred forty-nine".