20917829 has 2 divisors, whose sum is σ = 20917830. Its totient is φ = 20917828.

The previous prime is 20917811. The next prime is 20917843. The reversal of 20917829 is 92871902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12496225 + 8421604 = 3535^2 + 2902^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20917829 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20917792 and 20917801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20917849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10458914 + 10458915.

It is an arithmetic number, because the mean of its divisors is an integer number (10458915).

Almost surely, 2^20917829 is an apocalyptic number.

It is an amenable number.

20917829 is a deficient number, since it is larger than the sum of its proper divisors (1).

20917829 is an equidigital number, since it uses as much as digits as its factorization.

20917829 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 20917829 is about 4573.6013162496. The cubic root of 20917829 is about 275.5321003480.

The spelling of 20917829 in words is "twenty million, nine hundred seventeen thousand, eight hundred twenty-nine".