20729823 has 4 divisors (see below), whose sum is σ = 27639768. Its totient is φ = 13819880.

The previous prime is 20729789. The next prime is 20729861. The reversal of 20729823 is 32892702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20729823 - 2⁸ = 20729567 is a prime.

It is a super-2 number, since 2×20729823² = 859451123222658, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20729873) 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 3 ways as a sum of consecutive naturals, for example, 3454968 + ... + 3454973.

It is an arithmetic number, because the mean of its divisors is an integer number (6909942).

Almost surely, 2^20729823 is an apocalyptic number.

20729823 is a deficient number, since it is larger than the sum of its proper divisors (6909945).

20729823 is an equidigital number, since it uses as much as digits as its factorization.

20729823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6909944.

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 20729823 is about 4553.0015374476. The cubic root of 20729823 is about 274.7041357973.

The spelling of 20729823 in words is "twenty million, seven hundred twenty-nine thousand, eight hundred twenty-three".