28720811 has 6 divisors (see below), whose sum is σ = 33409980. Its totient is φ = 24617796.

The previous prime is 28720801. The next prime is 28720819. The reversal of 28720811 is 11802782.

It is not a de Polignac number, because 28720811 - 2¹⁰ = 28719787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28720819) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 293021 + ... + 293118.

It is an arithmetic number, because the mean of its divisors is an integer number (5568330).

Almost surely, 2^28720811 is an apocalyptic number.

28720811 is a deficient number, since it is larger than the sum of its proper divisors (4689169).

28720811 is an equidigital number, since it uses as much as digits as its factorization.

28720811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 586153 (or 586146 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 28720811 is about 5359.1800678835. The cubic root of 28720811 is about 306.2425739696.

The spelling of 28720811 in words is "twenty-eight million, seven hundred twenty thousand, eight hundred eleven".