20871729 has 8 divisors (see below), whose sum is σ = 30921120. Its totient is φ = 13914468.

The previous prime is 20871707. The next prime is 20871731. The reversal of 20871729 is 92717802.

It is not a de Polignac number, because 20871729 - 2⁹ = 20871217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20871693 and 20871702.

It is not an unprimeable number, because it can be changed into a prime (20871769) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 386487 + ... + 386540.

It is an arithmetic number, because the mean of its divisors is an integer number (3865140).

Almost surely, 2^20871729 is an apocalyptic number.

It is an amenable number.

20871729 is a deficient number, since it is larger than the sum of its proper divisors (10049391).

20871729 is an equidigital number, since it uses as much as digits as its factorization.

20871729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 773036 (or 773030 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 20871729 is about 4568.5587442869. The cubic root of 20871729 is about 275.3295399319.

The spelling of 20871729 in words is "twenty million, eight hundred seventy-one thousand, seven hundred twenty-nine".