866155805450638 has 4 divisors (see below), whose sum is σ = 1299233708175960. Its totient is φ = 433077902725318.

The previous prime is 866155805450549. The next prime is 866155805450687. The reversal of 866155805450638 is 836054508551668.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 216538951362658 + ... + 216538951362661.

It is an arithmetic number, because the mean of its divisors is an integer number (324808427043990).

Almost surely, 2^{866155805450638} is an apocalyptic number.

866155805450638 is a deficient number, since it is larger than the sum of its proper divisors (433077902725322).

866155805450638 is a wasteful number, since it uses less digits than its factorization.

866155805450638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 433077902725321.

The product of its (nonzero) digits is 829440000, while the sum is 70.

The spelling of 866155805450638 in words is "eight hundred sixty-six trillion, one hundred fifty-five billion, eight hundred five million, four hundred fifty thousand, six hundred thirty-eight".