21987651282743 has 2 divisors, whose sum is σ = 21987651282744. Its totient is φ = 21987651282742.

The previous prime is 21987651282731. The next prime is 21987651282767. The reversal of 21987651282743 is 34728215678912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21987651282743 - 2⁶ = 21987651282679 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21987651282743.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21987651282713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993825641371 + 10993825641372.

It is an arithmetic number, because the mean of its divisors is an integer number (10993825641372).

Almost surely, 2^{21987651282743} is an apocalyptic number.

21987651282743 is a deficient number, since it is larger than the sum of its proper divisors (1).

21987651282743 is an equidigital number, since it uses as much as digits as its factorization.

21987651282743 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81285120, while the sum is 65.

The spelling of 21987651282743 in words is "twenty-one trillion, nine hundred eighty-seven billion, six hundred fifty-one million, two hundred eighty-two thousand, seven hundred forty-three".