20627821 has 4 divisors (see below), whose sum is σ = 20966044. Its totient is φ = 20289600.

The previous prime is 20627819. The next prime is 20627839. The reversal of 20627821 is 12872602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12872602 = 2 ⋅6436301.

It can be written as a sum of positive squares in 2 ways, for example, as 7918596 + 12709225 = 2814^2 + 3565^2 .

It is a cyclic number.

It is not a de Polignac number, because 20627821 - 2¹ = 20627819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20627821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20627801) 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, 169020 + ... + 169141.

It is an arithmetic number, because the mean of its divisors is an integer number (5241511).

Almost surely, 2^20627821 is an apocalyptic number.

It is an amenable number.

20627821 is a deficient number, since it is larger than the sum of its proper divisors (338223).

20627821 is an equidigital number, since it uses as much as digits as its factorization.

20627821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338222.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 20627821 is about 4541.7861024051. The cubic root of 20627821 is about 274.2528301945.

The spelling of 20627821 in words is "twenty million, six hundred twenty-seven thousand, eight hundred twenty-one".