28161778 has 16 divisors (see below), whose sum is σ = 42771456. Its totient is φ = 13906080.

The previous prime is 28161769. The next prime is 28161779. The reversal of 28161778 is 87716182.

It is a self number, because there is not a number n which added to its sum of digits gives 28161778.

It is not an unprimeable number, because it can be changed into a prime (28161779) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103783 + ... + 104053.

It is an arithmetic number, because the mean of its divisors is an integer number (2673216).

Almost surely, 2^28161778 is an apocalyptic number.

28161778 is a deficient number, since it is larger than the sum of its proper divisors (14609678).

28161778 is a wasteful number, since it uses less digits than its factorization.

28161778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729.

The product of its digits is 37632, while the sum is 40.

The square root of 28161778 is about 5306.7671891652. The cubic root of 28161778 is about 304.2425998033.

The spelling of 28161778 in words is "twenty-eight million, one hundred sixty-one thousand, seven hundred seventy-eight".