2171561020655 has 48 divisors (see below), whose sum is σ = 2980508737536. Its totient is φ = 1515793668480.

The previous prime is 2171561020621. The next prime is 2171561020669. The reversal of 2171561020655 is 5560201651712.

It is not a de Polignac number, because 2171561020655 - 2⁸ = 2171561020399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 162434 + ... + 2090336.

It is an arithmetic number, because the mean of its divisors is an integer number (62093932032).

Almost surely, 2^{2171561020655} is an apocalyptic number.

2171561020655 is a deficient number, since it is larger than the sum of its proper divisors (808947716881).

2171561020655 is a wasteful number, since it uses less digits than its factorization.

2171561020655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1928008 (or 1927995 counting only the distinct ones).

The product of its (nonzero) digits is 126000, while the sum is 41.

The spelling of 2171561020655 in words is "two trillion, one hundred seventy-one billion, five hundred sixty-one million, twenty thousand, six hundred fifty-five".