21388718447 has 2 divisors, whose sum is σ = 21388718448. Its totient is φ = 21388718446.

The previous prime is 21388718441. The next prime is 21388718459. The reversal of 21388718447 is 74481788312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21388718447 - 2¹⁶ = 21388652911 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21388718441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10694359223 + 10694359224.

It is an arithmetic number, because the mean of its divisors is an integer number (10694359224).

Almost surely, 2^21388718447 is an apocalyptic number.

21388718447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21388718447 is an equidigital number, since it uses as much as digits as its factorization.

21388718447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2408448, while the sum is 53.

The spelling of 21388718447 in words is "twenty-one billion, three hundred eighty-eight million, seven hundred eighteen thousand, four hundred forty-seven".