166820471977 has 4 divisors (see below), whose sum is σ = 174073536000. Its totient is φ = 159567407956.

The previous prime is 166820471947. The next prime is 166820472053. The reversal of 166820471977 is 779174028661.

It is a happy number.

166820471977 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 166820471977 - 2²³ = 166812083369 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166820471947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3626531977 + ... + 3626532022.

It is an arithmetic number, because the mean of its divisors is an integer number (43518384000).

Almost surely, 2^166820471977 is an apocalyptic number.

It is an amenable number.

166820471977 is a deficient number, since it is larger than the sum of its proper divisors (7253064023).

166820471977 is an equidigital number, since it uses as much as digits as its factorization.

166820471977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7253064022.

The product of its (nonzero) digits is 7112448, while the sum is 58.

The spelling of 166820471977 in words is "one hundred sixty-six billion, eight hundred twenty million, four hundred seventy-one thousand, nine hundred seventy-seven".