28470781 has 4 divisors (see below), whose sum is σ = 28618492. Its totient is φ = 28323072.

The previous prime is 28470763. The next prime is 28470791. The reversal of 28470781 is 18707482.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18707482 = 2 ⋅9353741.

It can be written as a sum of positive squares in 2 ways, for example, as 10272025 + 18198756 = 3205^2 + 4266^2 .

It is a cyclic number.

It is not a de Polignac number, because 28470781 - 2⁵ = 28470749 is a prime.

It is a super-2 number, since 2×28470781² = 1621170741499922, which contains 22 as substring.

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 28470781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28470751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73566 + ... + 73951.

It is an arithmetic number, because the mean of its divisors is an integer number (7154623).

Almost surely, 2^28470781 is an apocalyptic number.

It is an amenable number.

28470781 is a deficient number, since it is larger than the sum of its proper divisors (147711).

28470781 is a wasteful number, since it uses less digits than its factorization.

28470781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147710.

The product of its (nonzero) digits is 25088, while the sum is 37.

The square root of 28470781 is about 5335.8018141606. The cubic root of 28470781 is about 305.3513142552.

The spelling of 28470781 in words is "twenty-eight million, four hundred seventy thousand, seven hundred eighty-one".