165655681551 has 20 divisors (see below), whose sum is σ = 258220131312. Its totient is φ = 105635505888.

The previous prime is 165655681469. The next prime is 165655681591. The reversal of 165655681551 is 155186556561.

165655681551 is a `hidden beast` number, since 1 + 6 + 5 + 6 + 5 + 5 + 6 + 81 + 551 = 666.

It is not a de Polignac number, because 165655681551 - 2⁹ = 165655681039 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165655681591) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 44457526 + ... + 44461251.

Almost surely, 2^165655681551 is an apocalyptic number.

165655681551 is a deficient number, since it is larger than the sum of its proper divisors (92564449761).

165655681551 is an equidigital number, since it uses as much as digits as its factorization.

165655681551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88918812 (or 88918803 counting only the distinct ones).

The product of its digits is 5400000, while the sum is 54.

The spelling of 165655681551 in words is "one hundred sixty-five billion, six hundred fifty-five million, six hundred eighty-one thousand, five hundred fifty-one".