1617777942561 has 27 divisors (see below), whose sum is σ = 2568604808497. Its totient is φ = 980446041960.

The previous prime is 1617777942509. The next prime is 1617777942569. The reversal of 1617777942561 is 1652497777161.

It is a happy number.

The square root of 1617777942561 is 1271919.

It is a perfect power (a square), and thus also a powerful number.

1617777942561 is a `hidden beast` number, since 1 + 6 + 17 + 77 + 79 + 425 + 61 = 666.

It is not a de Polignac number, because 1617777942561 - 2⁹ = 1617777942049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1617777942569) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 41954056 + ... + 41992598.

Almost surely, 2^{1617777942561} is an apocalyptic number.

1617777942561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1617777942561 is the 1271919-th square number.

1617777942561 is the 635960-th centered octagonal number.

It is an amenable number.

1617777942561 is a deficient number, since it is larger than the sum of its proper divisors (950826865936).

1617777942561 is an frugal number, since it uses more digits than its factorization.

1617777942561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77114 (or 38557 counting only the distinct ones).

The product of its digits is 31116960, while the sum is 63.

The spelling of 1617777942561 in words is "one trillion, six hundred seventeen billion, seven hundred seventy-seven million, nine hundred forty-two thousand, five hundred sixty-one".