20720731 has 2 divisors, whose sum is σ = 20720732. Its totient is φ = 20720730.

The previous prime is 20720719. The next prime is 20720743. The reversal of 20720731 is 13702702.

It is a balanced prime because it is at equal distance from previous prime (20720719) and next prime (20720743).

It is a cyclic number.

It is not a de Polignac number, because 20720731 - 2¹⁹ = 20196443 is a prime.

It is a super-2 number, since 2×20720731² = 858697386348722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20720771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10360365 + 10360366.

It is an arithmetic number, because the mean of its divisors is an integer number (10360366).

Almost surely, 2^20720731 is an apocalyptic number.

20720731 is a deficient number, since it is larger than the sum of its proper divisors (1).

20720731 is an equidigital number, since it uses as much as digits as its factorization.

20720731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 588, while the sum is 22.

The square root of 20720731 is about 4552.0029657284. The cubic root of 20720731 is about 274.6639686230.

The spelling of 20720731 in words is "twenty million, seven hundred twenty thousand, seven hundred thirty-one".