28991011 has 4 divisors (see below), whose sum is σ = 33132592. Its totient is φ = 24849432.

The previous prime is 28991009. The next prime is 28991021. The reversal of 28991011 is 11019982.

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

It is a cyclic number.

It is not a de Polignac number, because 28991011 - 2¹ = 28991009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28991021) 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, 2070780 + ... + 2070793.

It is an arithmetic number, because the mean of its divisors is an integer number (8283148).

Almost surely, 2^28991011 is an apocalyptic number.

28991011 is a deficient number, since it is larger than the sum of its proper divisors (4141581).

28991011 is an equidigital number, since it uses as much as digits as its factorization.

28991011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4141580.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 28991011 is about 5384.3301347521. The cubic root of 28991011 is about 307.1999355457.

The spelling of 28991011 in words is "twenty-eight million, nine hundred ninety-one thousand, eleven".