20998729 has 2 divisors, whose sum is σ = 20998730. Its totient is φ = 20998728.

The previous prime is 20998727. The next prime is 20998739. The reversal of 20998729 is 92789902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18688329 + 2310400 = 4323^2 + 1520^2 .

It is a cyclic number.

It is not a de Polignac number, because 20998729 - 2¹ = 20998727 is a prime.

Together with 20998727, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20998727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10499364 + 10499365.

It is an arithmetic number, because the mean of its divisors is an integer number (10499365).

Almost surely, 2^20998729 is an apocalyptic number.

It is an amenable number.

20998729 is a deficient number, since it is larger than the sum of its proper divisors (1).

20998729 is an equidigital number, since it uses as much as digits as its factorization.

20998729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 163296, while the sum is 46.

The square root of 20998729 is about 4582.4370153882. The cubic root of 20998729 is about 275.8868515058.

The spelling of 20998729 in words is "twenty million, nine hundred ninety-eight thousand, seven hundred twenty-nine".