28724283781 has 4 divisors (see below), whose sum is σ = 28725086700. Its totient is φ = 28723480864.

The previous prime is 28724283779. The next prime is 28724283799. The reversal of 28724283781 is 18738242782.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3191120100 + 25533163681 = 56490^2 + 159791^2 .

It is a cyclic number.

It is not a de Polignac number, because 28724283781 - 2¹ = 28724283779 is a prime.

It is a super-2 number, since 2×28724283781² (a number of 22 digits) 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 (28724283481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 345166 + ... + 420223.

It is an arithmetic number, because the mean of its divisors is an integer number (7181271675).

Almost surely, 2^28724283781 is an apocalyptic number.

It is an amenable number.

28724283781 is a deficient number, since it is larger than the sum of its proper divisors (802919).

28724283781 is an equidigital number, since it uses as much as digits as its factorization.

28724283781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 802918.

The product of its digits is 2408448, while the sum is 52.

The spelling of 28724283781 in words is "twenty-eight billion, seven hundred twenty-four million, two hundred eighty-three thousand, seven hundred eighty-one".