20720823 has 4 divisors (see below), whose sum is σ = 27627768. Its totient is φ = 13813880.

The previous prime is 20720789. The next prime is 20720893. The reversal of 20720823 is 32802702.

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 20720823 - 2⁶ = 20720759 is a prime.

It is a super-5 number, since 5×20720823⁵ (a number of 38 digits) contains 55555 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20720793 and 20720802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20720893) 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, 3453468 + ... + 3453473.

It is an arithmetic number, because the mean of its divisors is an integer number (6906942).

Almost surely, 2^20720823 is an apocalyptic number.

20720823 is a deficient number, since it is larger than the sum of its proper divisors (6906945).

20720823 is an equidigital number, since it uses as much as digits as its factorization.

20720823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6906944.

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 20720823 is about 4552.0130711587. The cubic root of 20720823 is about 274.6643751249.

The spelling of 20720823 in words is "twenty million, seven hundred twenty thousand, eight hundred twenty-three".