2105620665521 has 2 divisors, whose sum is σ = 2105620665522. Its totient is φ = 2105620665520.

The previous prime is 2105620665517. The next prime is 2105620665679. The reversal of 2105620665521 is 1255660265012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1691703429025 + 413917236496 = 1300655^2 + 643364^2 .

It is a cyclic number.

It is not a de Polignac number, because 2105620665521 - 2² = 2105620665517 is a prime.

It is not a weakly prime, because it can be changed into another prime (2105620665121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1052810332760 + 1052810332761.

It is an arithmetic number, because the mean of its divisors is an integer number (1052810332761).

Almost surely, 2^{2105620665521} is an apocalyptic number.

It is an amenable number.

2105620665521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2105620665521 is an equidigital number, since it uses as much as digits as its factorization.

2105620665521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216000, while the sum is 41.

The spelling of 2105620665521 in words is "two trillion, one hundred five billion, six hundred twenty million, six hundred sixty-five thousand, five hundred twenty-one".