21555029 has 2 divisors, whose sum is σ = 21555030. Its totient is φ = 21555028.

The previous prime is 21555007. The next prime is 21555041. The reversal of 21555029 is 92055512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12567025 + 8988004 = 3545^2 + 2998^2 .

It is a cyclic number.

It is not a de Polignac number, because 21555029 - 2⁸ = 21554773 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21554992 and 21555010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21555829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777514 + 10777515.

It is an arithmetic number, because the mean of its divisors is an integer number (10777515).

Almost surely, 2^21555029 is an apocalyptic number.

It is an amenable number.

21555029 is a deficient number, since it is larger than the sum of its proper divisors (1).

21555029 is an equidigital number, since it uses as much as digits as its factorization.

21555029 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4500, while the sum is 29.

The square root of 21555029 is about 4642.7393853198. The cubic root of 21555029 is about 278.3019208297.

The spelling of 21555029 in words is "twenty-one million, five hundred fifty-five thousand, twenty-nine".