20841957421 has 2 divisors, whose sum is σ = 20841957422. Its totient is φ = 20841957420.

The previous prime is 20841957419. The next prime is 20841957457. The reversal of 20841957421 is 12475914802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12879072196 + 7962885225 = 113486^2 + 89235^2 .

It is a cyclic number.

It is not a de Polignac number, because 20841957421 - 2¹ = 20841957419 is a prime.

Together with 20841957419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20841957401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10420978710 + 10420978711.

It is an arithmetic number, because the mean of its divisors is an integer number (10420978711).

Almost surely, 2^20841957421 is an apocalyptic number.

It is an amenable number.

20841957421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20841957421 is an equidigital number, since it uses as much as digits as its factorization.

20841957421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 161280, while the sum is 43.

The spelling of 20841957421 in words is "twenty billion, eight hundred forty-one million, nine hundred fifty-seven thousand, four hundred twenty-one".