28656781 has 8 divisors (see below), whose sum is σ = 31662144. Its totient is φ = 25798080.

The previous prime is 28656779. The next prime is 28656787. The reversal of 28656781 is 18765682.

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 28656781 - 2¹ = 28656779 is a prime.

It is a super-2 number, since 2×28656781² = 1642422194563922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28656787) 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, 36255 + ... + 37036.

It is an arithmetic number, because the mean of its divisors is an integer number (3957768).

Almost surely, 2^28656781 is an apocalyptic number.

It is an amenable number.

28656781 is a deficient number, since it is larger than the sum of its proper divisors (3005363).

28656781 is a wasteful number, since it uses less digits than its factorization.

28656781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73331.

The product of its digits is 161280, while the sum is 43.

The square root of 28656781 is about 5353.2028730471. The cubic root of 28656781 is about 306.0148262001.

The spelling of 28656781 in words is "twenty-eight million, six hundred fifty-six thousand, seven hundred eighty-one".