28636991 has 8 divisors (see below), whose sum is σ = 28930944. Its totient is φ = 28344960.

The previous prime is 28636967. The next prime is 28636997. The reversal of 28636991 is 19963682.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28636991 - 2¹⁰ = 28635967 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28636997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62435 + ... + 62891.

It is an arithmetic number, because the mean of its divisors is an integer number (3616368).

Almost surely, 2^28636991 is an apocalyptic number.

28636991 is a deficient number, since it is larger than the sum of its proper divisors (293953).

28636991 is a wasteful number, since it uses less digits than its factorization.

28636991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 961.

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

The square root of 28636991 is about 5351.3541276952. The cubic root of 28636991 is about 305.9443666927.

The spelling of 28636991 in words is "twenty-eight million, six hundred thirty-six thousand, nine hundred ninety-one".