21987642483743 has 2 divisors, whose sum is σ = 21987642483744. Its totient is φ = 21987642483742.

The previous prime is 21987642483739. The next prime is 21987642483749. The reversal of 21987642483743 is 34738424678912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21987642483743 - 2² = 21987642483739 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21987642483749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993821241871 + 10993821241872.

It is an arithmetic number, because the mean of its divisors is an integer number (10993821241872).

Almost surely, 2^{21987642483743} is an apocalyptic number.

21987642483743 is a deficient number, since it is larger than the sum of its proper divisors (1).

21987642483743 is an equidigital number, since it uses as much as digits as its factorization.

21987642483743 is an evil number, because the sum of its binary digits is even.

The product of its digits is 390168576, while the sum is 68.

The spelling of 21987642483743 in words is "twenty-one trillion, nine hundred eighty-seven billion, six hundred forty-two million, four hundred eighty-three thousand, seven hundred forty-three".