28720737 has 20 divisors (see below), whose sum is σ = 43310740. Its totient is φ = 18965664.

The previous prime is 28720717. The next prime is 28720777. The reversal of 28720737 is 73702782.

It can be written as a sum of positive squares in 2 ways, for example, as 25765776 + 2954961 = 5076^2 + 1719^2 .

It is not a de Polignac number, because 28720737 - 2⁶ = 28720673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28720717) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 7203 + ... + 10455.

It is an arithmetic number, because the mean of its divisors is an integer number (2165537).

Almost surely, 2^28720737 is an apocalyptic number.

28720737 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

28720737 is a deficient number, since it is larger than the sum of its proper divisors (14590003).

28720737 is a wasteful number, since it uses less digits than its factorization.

28720737 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3374 (or 3365 counting only the distinct ones).

The product of its (nonzero) digits is 32928, while the sum is 36.

The square root of 28720737 is about 5359.1731638379. The cubic root of 28720737 is about 306.2423109551.

The spelling of 28720737 in words is "twenty-eight million, seven hundred twenty thousand, seven hundred thirty-seven".