28431638 has 24 divisors (see below), whose sum is σ = 45921168. Its totient is φ = 13195728.

The previous prime is 28431589. The next prime is 28431647. The reversal of 28431638 is 83613482.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 28431598 and 28431607.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37895 + ... + 38637.

It is an arithmetic number, because the mean of its divisors is an integer number (1913382).

Almost surely, 2^28431638 is an apocalyptic number.

28431638 is a deficient number, since it is larger than the sum of its proper divisors (17489530).

28431638 is a wasteful number, since it uses less digits than its factorization.

28431638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 836 (or 817 counting only the distinct ones).

The product of its digits is 27648, while the sum is 35.

The square root of 28431638 is about 5332.1325940003. The cubic root of 28431638 is about 305.2113128477.

The spelling of 28431638 in words is "twenty-eight million, four hundred thirty-one thousand, six hundred thirty-eight".