20343721 has 4 divisors (see below), whose sum is σ = 20373444. Its totient is φ = 20314000.

The previous prime is 20343689. The next prime is 20343727. The reversal of 20343721 is 12734302.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19053225 + 1290496 = 4365^2 + 1136^2 .

It is a cyclic number.

It is not a de Polignac number, because 20343721 - 2⁵ = 20343689 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20343692 and 20343701.

It is not an unprimeable number, because it can be changed into a prime (20343727) 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, 13810 + ... + 15211.

It is an arithmetic number, because the mean of its divisors is an integer number (5093361).

Almost surely, 2^20343721 is an apocalyptic number.

It is an amenable number.

20343721 is a deficient number, since it is larger than the sum of its proper divisors (29723).

20343721 is an equidigital number, since it uses as much as digits as its factorization.

20343721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29722.

The product of its (nonzero) digits is 1008, while the sum is 22.

The square root of 20343721 is about 4510.4014233769. The cubic root of 20343721 is about 272.9879415213.

The spelling of 20343721 in words is "twenty million, three hundred forty-three thousand, seven hundred twenty-one".