28491287 has 4 divisors (see below), whose sum is σ = 31081416. Its totient is φ = 25901160.

The previous prime is 28491283. The next prime is 28491289. The reversal of 28491287 is 78219482.

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 28491287 - 2² = 28491283 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 (28491283) 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, 1295048 + ... + 1295069.

It is an arithmetic number, because the mean of its divisors is an integer number (7770354).

Almost surely, 2^28491287 is an apocalyptic number.

28491287 is a deficient number, since it is larger than the sum of its proper divisors (2590129).

28491287 is a wasteful number, since it uses less digits than its factorization.

28491287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2590128.

The product of its digits is 64512, while the sum is 41.

The square root of 28491287 is about 5337.7230164181. The cubic root of 28491287 is about 305.4246061373.

It can be divided in two parts, 2849 and 1287, that multiplied together give a palindrome (3666663).

The spelling of 28491287 in words is "twenty-eight million, four hundred ninety-one thousand, two hundred eighty-seven".