168405561 has 16 divisors (see below), whose sum is σ = 252573120. Its totient is φ = 112268916.

The previous prime is 168405557. The next prime is 168405571. The reversal of 168405561 is 165504861.

168405561 is a `hidden beast` number, since 1 + 68 + 40 + 556 + 1 = 666.

It is not a de Polignac number, because 168405561 - 2² = 168405557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (168405511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36315 + ... + 40688.

It is an arithmetic number, because the mean of its divisors is an integer number (15785820).

Almost surely, 2^168405561 is an apocalyptic number.

It is an amenable number.

168405561 is a deficient number, since it is larger than the sum of its proper divisors (84167559).

168405561 is an frugal number, since it uses more digits than its factorization.

168405561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77024 (or 77006 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 168405561 is about 12977.1168215440. The cubic root of 168405561 is about 552.2284911819.

The spelling of 168405561 in words is "one hundred sixty-eight million, four hundred five thousand, five hundred sixty-one".