20917823 has 8 divisors (see below), whose sum is σ = 21508608. Its totient is φ = 20331864.

The previous prime is 20917811. The next prime is 20917829. The reversal of 20917823 is 32871902.

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 20917823 - 2²⁴ = 4140607 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20917823.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20917829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8690 + ... + 10832.

It is an arithmetic number, because the mean of its divisors is an integer number (2688576).

Almost surely, 2^20917823 is an apocalyptic number.

20917823 is a deficient number, since it is larger than the sum of its proper divisors (590785).

20917823 is a wasteful number, since it uses less digits than its factorization.

20917823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2413.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 20917823 is about 4573.6006603113. The cubic root of 20917823 is about 275.5320740038.

The spelling of 20917823 in words is "twenty million, nine hundred seventeen thousand, eight hundred twenty-three".