20931729 has 16 divisors (see below), whose sum is σ = 34349952. Its totient is φ = 11040768.

The previous prime is 20931721. The next prime is 20931731. The reversal of 20931729 is 92713902.

It is not a de Polignac number, because 20931729 - 2³ = 20931721 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20931729.

It is not an unprimeable number, because it can be changed into a prime (20931721) 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 15 ways as a sum of consecutive naturals, for example, 38064 + ... + 38609.

It is an arithmetic number, because the mean of its divisors is an integer number (2146872).

Almost surely, 2^20931729 is an apocalyptic number.

It is an amenable number.

20931729 is a deficient number, since it is larger than the sum of its proper divisors (13418223).

20931729 is a wasteful number, since it uses less digits than its factorization.

20931729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76696.

The product of its (nonzero) digits is 6804, while the sum is 33.

The square root of 20931729 is about 4575.1206541467. The cubic root of 20931729 is about 275.5931176454.

The spelling of 20931729 in words is "twenty million, nine hundred thirty-one thousand, seven hundred twenty-nine".