20729993 has 2 divisors, whose sum is σ = 20729994. Its totient is φ = 20729992.

The previous prime is 20729981. The next prime is 20730011. The reversal of 20729993 is 39992702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20539024 + 190969 = 4532^2 + 437^2 .

It is a cyclic number.

It is not a de Polignac number, because 20729993 - 2¹⁰ = 20728969 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20729993.

It is not a weakly prime, because it can be changed into another prime (20729903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10364996 + 10364997.

It is an arithmetic number, because the mean of its divisors is an integer number (10364997).

Almost surely, 2^20729993 is an apocalyptic number.

It is an amenable number.

20729993 is a deficient number, since it is larger than the sum of its proper divisors (1).

20729993 is an equidigital number, since it uses as much as digits as its factorization.

20729993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 41.

The square root of 20729993 is about 4553.0202064124. The cubic root of 20729993 is about 274.7048867214.

The spelling of 20729993 in words is "twenty million, seven hundred twenty-nine thousand, nine hundred ninety-three".