20720831 has 8 divisors (see below), whose sum is σ = 21276480. Its totient is φ = 20172672.

The previous prime is 20720789. The next prime is 20720893. The reversal of 20720831 is 13802702.

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 20720831 - 2⁶ = 20720767 is a prime.

It is a super-2 number, since 2×20720831² = 858705674661122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20720797 and 20720806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20720131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3971 + ... + 7563.

It is an arithmetic number, because the mean of its divisors is an integer number (2659560).

Almost surely, 2^20720831 is an apocalyptic number.

20720831 is a deficient number, since it is larger than the sum of its proper divisors (555649).

20720831 is an equidigital number, since it uses as much as digits as its factorization.

20720831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3745.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 20720831 is about 4552.0139498908. The cubic root of 20720831 is about 274.6644104728.

The spelling of 20720831 in words is "twenty million, seven hundred twenty thousand, eight hundred thirty-one".