20073721 has 4 divisors (see below), whose sum is σ = 20616292. Its totient is φ = 19531152.

The previous prime is 20073707. The next prime is 20073731. The reversal of 20073721 is 12737002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12737002 = 2 ⋅6368501.

It can be written as a sum of positive squares in 2 ways, for example, as 15912121 + 4161600 = 3989^2 + 2040^2 .

It is a cyclic number.

It is not a de Polignac number, because 20073721 - 2⁷ = 20073593 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20073692 and 20073701.

It is not an unprimeable number, because it can be changed into a prime (20073731) 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 in 3 ways as a sum of consecutive naturals, for example, 271230 + ... + 271303.

It is an arithmetic number, because the mean of its divisors is an integer number (5154073).

Almost surely, 2^20073721 is an apocalyptic number.

It is an amenable number.

20073721 is a deficient number, since it is larger than the sum of its proper divisors (542571).

20073721 is an equidigital number, since it uses as much as digits as its factorization.

20073721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542570.

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

The square root of 20073721 is about 4480.3706319902. The cubic root of 20073721 is about 271.7748686796.

The spelling of 20073721 in words is "twenty million, seventy-three thousand, seven hundred twenty-one".