28781213 has 8 divisors (see below), whose sum is σ = 29151168. Its totient is φ = 28413504.

The previous prime is 28781209. The next prime is 28781239. The reversal of 28781213 is 31218782.

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 28781213 - 2² = 28781209 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28781213.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28781243) 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, 54770 + ... + 55292.

It is an arithmetic number, because the mean of its divisors is an integer number (3643896).

Almost surely, 2^28781213 is an apocalyptic number.

It is an amenable number.

28781213 is a deficient number, since it is larger than the sum of its proper divisors (369955).

28781213 is a wasteful number, since it uses less digits than its factorization.

28781213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1123.

The product of its digits is 5376, while the sum is 32.

The square root of 28781213 is about 5364.8124850735. The cubic root of 28781213 is about 306.4571072774.

Adding to 28781213 its reverse (31218782), we get a palindrome (59999995).

The spelling of 28781213 in words is "twenty-eight million, seven hundred eighty-one thousand, two hundred thirteen".