20416821 has 4 divisors (see below), whose sum is σ = 27222432. Its totient is φ = 13611212.

The previous prime is 20416807. The next prime is 20416829. The reversal of 20416821 is 12861402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20416821 - 2⁵ = 20416789 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20416791 and 20416800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20416829) 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, 3402801 + ... + 3402806.

It is an arithmetic number, because the mean of its divisors is an integer number (6805608).

Almost surely, 2^20416821 is an apocalyptic number.

It is an amenable number.

20416821 is a deficient number, since it is larger than the sum of its proper divisors (6805611).

20416821 is an equidigital number, since it uses as much as digits as its factorization.

20416821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6805610.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 20416821 is about 4518.4976485553. The cubic root of 20416821 is about 273.3145216414.

The spelling of 20416821 in words is "twenty million, four hundred sixteen thousand, eight hundred twenty-one".