166577768043991 has 12 divisors (see below), whose sum is σ = 171896303478312. Its totient is φ = 161365996141584.

The previous prime is 166577768043959. The next prime is 166577768044007. The reversal of 166577768043991 is 199340867775661.

It is not a de Polignac number, because 166577768043991 - 2⁵ = 166577768043959 is a prime.

It is a super-2 number, since 2×166577768043991² (a number of 29 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (79).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166577768043691) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 251469961 + ... + 252131506.

It is an arithmetic number, because the mean of its divisors is an integer number (14324691956526).

Almost surely, 2^{166577768043991} is an apocalyptic number.

166577768043991 is a deficient number, since it is larger than the sum of its proper divisors (5318535434321).

166577768043991 is an frugal number, since it uses more digits than its factorization.

166577768043991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503601678 (or 503601599 counting only the distinct ones).

The product of its (nonzero) digits is 2880541440, while the sum is 79.

The spelling of 166577768043991 in words is "one hundred sixty-six trillion, five hundred seventy-seven billion, seven hundred sixty-eight million, forty-three thousand, nine hundred ninety-one".