166861647477 has 24 divisors (see below), whose sum is σ = 284952570240. Its totient is φ = 92061597600.

The previous prime is 166861647467. The next prime is 166861647541. The reversal of 166861647477 is 774746168661.

166861647477 is a `hidden beast` number, since 1 + 6 + 6 + 8 + 616 + 4 + 7 + 4 + 7 + 7 = 666.

It is not a de Polignac number, because 166861647477 - 2¹² = 166861643381 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166861647457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 45663649 + ... + 45667302.

It is an arithmetic number, because the mean of its divisors is an integer number (11873023760).

Almost surely, 2^166861647477 is an apocalyptic number.

It is an amenable number.

166861647477 is a deficient number, since it is larger than the sum of its proper divisors (118090922763).

166861647477 is a wasteful number, since it uses less digits than its factorization.

166861647477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91330993 (or 91330990 counting only the distinct ones).

The product of its digits is 56899584, while the sum is 63.

The spelling of 166861647477 in words is "one hundred sixty-six billion, eight hundred sixty-one million, six hundred forty-seven thousand, four hundred seventy-seven".