28006997 has 4 divisors (see below), whose sum is σ = 28284396. Its totient is φ = 27729600.

The previous prime is 28006987. The next prime is 28007017. The reversal of 28006997 is 79960082.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19280881 + 8726116 = 4391^2 + 2954^2 .

It is a cyclic number.

It is not a de Polignac number, because 28006997 - 2¹² = 28002901 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 (28006967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138548 + ... + 138749.

It is an arithmetic number, because the mean of its divisors is an integer number (7071099).

Almost surely, 2^28006997 is an apocalyptic number.

It is an amenable number.

28006997 is a deficient number, since it is larger than the sum of its proper divisors (277399).

28006997 is a wasteful number, since it uses less digits than its factorization.

28006997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277398.

The product of its (nonzero) digits is 54432, while the sum is 41.

The square root of 28006997 is about 5292.1637351843. The cubic root of 28006997 is about 303.6841891441.

The spelling of 28006997 in words is "twenty-eight million, six thousand, nine hundred ninety-seven".