28139966 has 4 divisors (see below), whose sum is σ = 42209952. Its totient is φ = 14069982.

The previous prime is 28139963. The next prime is 28139977. The reversal of 28139966 is 66993182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66993182 = 2 ⋅33496591.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28139963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7034990 + ... + 7034993.

It is an arithmetic number, because the mean of its divisors is an integer number (10552488).

Almost surely, 2^28139966 is an apocalyptic number.

28139966 is a deficient number, since it is larger than the sum of its proper divisors (14069986).

28139966 is a wasteful number, since it uses less digits than its factorization.

28139966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14069985.

The product of its digits is 139968, while the sum is 44.

The square root of 28139966 is about 5304.7116792527. The cubic root of 28139966 is about 304.1640316863.

The spelling of 28139966 in words is "twenty-eight million, one hundred thirty-nine thousand, nine hundred sixty-six".