20316721 has 8 divisors (see below), whose sum is σ = 20945088. Its totient is φ = 19698000.

The previous prime is 20316713. The next prime is 20316761. The reversal of 20316721 is 12761302.

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 20316721 - 2³ = 20316713 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20316692 and 20316701.

It is not an unprimeable number, because it can be changed into a prime (20316701) 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, 1986 + ... + 6676.

It is an arithmetic number, because the mean of its divisors is an integer number (2618136).

Almost surely, 2^20316721 is an apocalyptic number.

It is an amenable number.

20316721 is a deficient number, since it is larger than the sum of its proper divisors (628367).

20316721 is an equidigital number, since it uses as much as digits as its factorization.

20316721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4823.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 20316721 is about 4507.4073479108. The cubic root of 20316721 is about 272.8671190229.

The spelling of 20316721 in words is "twenty million, three hundred sixteen thousand, seven hundred twenty-one".