20684641 has 2 divisors, whose sum is σ = 20684642. Its totient is φ = 20684640.

The previous prime is 20684639. The next prime is 20684647. The reversal of 20684641 is 14648602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14409616 + 6275025 = 3796^2 + 2505^2 .

It is a cyclic number.

It is not a de Polignac number, because 20684641 - 2¹ = 20684639 is a prime.

Together with 20684639, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20684647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10342320 + 10342321.

It is an arithmetic number, because the mean of its divisors is an integer number (10342321).

Almost surely, 2^20684641 is an apocalyptic number.

It is an amenable number.

20684641 is a deficient number, since it is larger than the sum of its proper divisors (1).

20684641 is an equidigital number, since it uses as much as digits as its factorization.

20684641 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 20684641 is about 4548.0370491015. The cubic root of 20684641 is about 274.5044121020.

The spelling of 20684641 in words is "twenty million, six hundred eighty-four thousand, six hundred forty-one".