28723811866 has 4 divisors (see below), whose sum is σ = 43085717802. Its totient is φ = 14361905932.

The previous prime is 28723811863. The next prime is 28723811867. The reversal of 28723811866 is 66811832782.

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

It can be written as a sum of positive squares in only one way, i.e., 25114325625 + 3609486241 = 158475^2 + 60079^2 .

It is a super-2 number, since 2×28723811866² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28723811863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7180952965 + ... + 7180952968.

Almost surely, 2^28723811866 is an apocalyptic number.

28723811866 is a deficient number, since it is larger than the sum of its proper divisors (14361905936).

28723811866 is a wasteful number, since it uses less digits than its factorization.

28723811866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14361905935.

The product of its digits is 1548288, while the sum is 52.

The spelling of 28723811866 in words is "twenty-eight billion, seven hundred twenty-three million, eight hundred eleven thousand, eight hundred sixty-six".