20929717 has 4 divisors (see below), whose sum is σ = 20940300. Its totient is φ = 20919136.

The previous prime is 20929693. The next prime is 20929729. The reversal of 20929717 is 71792902.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 71792902 = 2 ⋅35896451.

It can be written as a sum of positive squares in 2 ways, for example, as 6482116 + 14447601 = 2546^2 + 3801^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20929717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20929817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1342 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (5235075).

Almost surely, 2^20929717 is an apocalyptic number.

It is an amenable number.

20929717 is a deficient number, since it is larger than the sum of its proper divisors (10583).

20929717 is an equidigital number, since it uses as much as digits as its factorization.

20929717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10582.

The product of its (nonzero) digits is 15876, while the sum is 37.

The square root of 20929717 is about 4574.9007639511. The cubic root of 20929717 is about 275.5842871737.

The spelling of 20929717 in words is "twenty million, nine hundred twenty-nine thousand, seven hundred seventeen".