28732391 has 4 divisors (see below), whose sum is σ = 28794912. Its totient is φ = 28669872.

The previous prime is 28732373. The next prime is 28732399. The reversal of 28732391 is 19323782.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28732391 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 (28732399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30566 + ... + 31491.

It is an arithmetic number, because the mean of its divisors is an integer number (7198728).

Almost surely, 2^28732391 is an apocalyptic number.

28732391 is a deficient number, since it is larger than the sum of its proper divisors (62521).

28732391 is an equidigital number, since it uses as much as digits as its factorization.

28732391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62520.

The product of its digits is 18144, while the sum is 35.

The square root of 28732391 is about 5360.2603481547. The cubic root of 28732391 is about 306.2837266202.

The spelling of 28732391 in words is "twenty-eight million, seven hundred thirty-two thousand, three hundred ninety-one".