21897453841 has 2 divisors, whose sum is σ = 21897453842. Its totient is φ = 21897453840.

The previous prime is 21897453839. The next prime is 21897453869. The reversal of 21897453841 is 14835479812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21311620225 + 585833616 = 145985^2 + 24204^2 .

It is a cyclic number.

It is not a de Polignac number, because 21897453841 - 2¹ = 21897453839 is a prime.

Together with 21897453839, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21897451841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10948726920 + 10948726921.

It is an arithmetic number, because the mean of its divisors is an integer number (10948726921).

Almost surely, 2^21897453841 is an apocalyptic number.

It is an amenable number.

21897453841 is a deficient number, since it is larger than the sum of its proper divisors (1).

21897453841 is an equidigital number, since it uses as much as digits as its factorization.

21897453841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1935360, while the sum is 52.

The spelling of 21897453841 in words is "twenty-one billion, eight hundred ninety-seven million, four hundred fifty-three thousand, eight hundred forty-one".