20654321 has 4 divisors (see below), whose sum is σ = 20663412. Its totient is φ = 20645232.

The previous prime is 20654287. The next prime is 20654323. The reversal of 20654321 is 12345602.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12345602 = 2 ⋅6172801.

It can be written as a sum of positive squares in 2 ways, for example, as 12503296 + 8151025 = 3536^2 + 2855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20654321 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20654323) 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, 2195 + ... + 6791.

It is an arithmetic number, because the mean of its divisors is an integer number (5165853).

Almost surely, 2^20654321 is an apocalyptic number.

It is an amenable number.

20654321 is a deficient number, since it is larger than the sum of its proper divisors (9091).

20654321 is an equidigital number, since it uses as much as digits as its factorization.

20654321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9090.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 20654321 is about 4544.7025205177. The cubic root of 20654321 is about 274.3702216536.

Adding to 20654321 its reverse (12345602), we get a palindrome (32999923).

The spelling of 20654321 in words is "twenty million, six hundred fifty-four thousand, three hundred twenty-one".