1661208920217 has 48 divisors (see below), whose sum is σ = 3064580588160. Its totient is φ = 841917715200.

The previous prime is 1661208920207. The next prime is 1661208920297. The reversal of 1661208920217 is 7120298021661.

1661208920217 is a `hidden beast` number, since 1 + 6 + 612 + 0 + 8 + 9 + 2 + 0 + 21 + 7 = 666.

It is not a de Polignac number, because 1661208920217 - 2¹⁴ = 1661208903833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1661208920207) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 29204842 + ... + 29261667.

It is an arithmetic number, because the mean of its divisors is an integer number (63845428920).

Almost surely, 2^{1661208920217} is an apocalyptic number.

It is an amenable number.

1661208920217 is a deficient number, since it is larger than the sum of its proper divisors (1403371667943).

1661208920217 is a wasteful number, since it uses less digits than its factorization.

1661208920217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58466574 (or 58466571 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The spelling of 1661208920217 in words is "one trillion, six hundred sixty-one billion, two hundred eight million, nine hundred twenty thousand, two hundred seventeen".