28904781 has 8 divisors (see below), whose sum is σ = 38564640. Its totient is φ = 19257392.

The previous prime is 28904773. The next prime is 28904783. The reversal of 28904781 is 18740982.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28904781 - 2³ = 28904773 is a prime.

It is a super-2 number, since 2×28904781² = 1670972729315922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28904783) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 6835 + ... + 10223.

It is an arithmetic number, because the mean of its divisors is an integer number (4820580).

Almost surely, 2^28904781 is an apocalyptic number.

It is an amenable number.

28904781 is a deficient number, since it is larger than the sum of its proper divisors (9659859).

28904781 is a wasteful number, since it uses less digits than its factorization.

28904781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6235.

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 28904781 is about 5376.3166759409. The cubic root of 28904781 is about 306.8950576249.

The spelling of 28904781 in words is "twenty-eight million, nine hundred four thousand, seven hundred eighty-one".