20503729 has 8 divisors (see below), whose sum is σ = 20928680. Its totient is φ = 20082816.

The previous prime is 20503709. The next prime is 20503753. The reversal of 20503729 is 92730502.

20503729 is nontrivially palindromic in base 4.

It can be written as a sum of positive squares in 4 ways, for example, as 6426225 + 14077504 = 2535^2 + 3752^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20503729 - 2⁵ = 20503697 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20503697 and 20503706.

It is not an unprimeable number, because it can be changed into a prime (20503709) 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 in 7 ways as a sum of consecutive naturals, for example, 10567 + ... + 12355.

It is an arithmetic number, because the mean of its divisors is an integer number (2616085).

Almost surely, 2^20503729 is an apocalyptic number.

It is an amenable number.

20503729 is a deficient number, since it is larger than the sum of its proper divisors (424951).

20503729 is a wasteful number, since it uses less digits than its factorization.

20503729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2019.

The product of its (nonzero) digits is 3780, while the sum is 28.

The square root of 20503729 is about 4528.1043495043. The cubic root of 20503729 is about 273.7017774013.

The spelling of 20503729 in words is "twenty million, five hundred three thousand, seven hundred twenty-nine".