28491457 has 4 divisors (see below), whose sum is σ = 29730240. Its totient is φ = 27252676.

The previous prime is 28491409. The next prime is 28491521. The reversal of 28491457 is 75419482.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28491457 - 2⁷ = 28491329 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28494457) 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, 619357 + ... + 619402.

It is an arithmetic number, because the mean of its divisors is an integer number (7432560).

Almost surely, 2^28491457 is an apocalyptic number.

It is an amenable number.

28491457 is a deficient number, since it is larger than the sum of its proper divisors (1238783).

28491457 is a wasteful number, since it uses less digits than its factorization.

28491457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1238782.

The product of its digits is 80640, while the sum is 40.

The square root of 28491457 is about 5337.7389407876. The cubic root of 28491457 is about 305.4252135988.

The spelling of 28491457 in words is "twenty-eight million, four hundred ninety-one thousand, four hundred fifty-seven".