21351108345761 has 2 divisors, whose sum is σ = 21351108345762. Its totient is φ = 21351108345760.

The previous prime is 21351108345719. The next prime is 21351108345793. The reversal of 21351108345761 is 16754380115312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21313743455761 + 37364890000 = 4616681^2 + 193300^2 .

It is a cyclic number.

It is not a de Polignac number, because 21351108345761 - 2²² = 21351104151457 is a prime.

It is not a weakly prime, because it can be changed into another prime (21351108345961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10675554172880 + 10675554172881.

It is an arithmetic number, because the mean of its divisors is an integer number (10675554172881).

Almost surely, 2^{21351108345761} is an apocalyptic number.

It is an amenable number.

21351108345761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21351108345761 is an equidigital number, since it uses as much as digits as its factorization.

21351108345761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 604800, while the sum is 47.

The spelling of 21351108345761 in words is "twenty-one trillion, three hundred fifty-one billion, one hundred eight million, three hundred forty-five thousand, seven hundred sixty-one".