21109979777699 has 2 divisors, whose sum is σ = 21109979777700. Its totient is φ = 21109979777698.

The previous prime is 21109979777657. The next prime is 21109979777753. The reversal of 21109979777699 is 99677797990112.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21109979777699 is a prime.

It is not a weakly prime, because it can be changed into another prime (21109979777639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554989888849 + 10554989888850.

It is an arithmetic number, because the mean of its divisors is an integer number (10554989888850).

Almost surely, 2^{21109979777699} is an apocalyptic number.

21109979777699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21109979777699 is an equidigital number, since it uses as much as digits as its factorization.

21109979777699 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1701319788, while the sum is 83.

The spelling of 21109979777699 in words is "twenty-one trillion, one hundred nine billion, nine hundred seventy-nine million, seven hundred seventy-seven thousand, six hundred ninety-nine".