28356781 has 2 divisors, whose sum is σ = 28356782. Its totient is φ = 28356780.

The previous prime is 28356773. The next prime is 28356787. The reversal of 28356781 is 18765382.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28355625 + 1156 = 5325^2 + 34^2 .

It is a cyclic number.

It is not a de Polignac number, because 28356781 - 2³ = 28356773 is a prime.

It is a super-2 number, since 2×28356781² = 1608214057363922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28356787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14178390 + 14178391.

It is an arithmetic number, because the mean of its divisors is an integer number (14178391).

Almost surely, 2^28356781 is an apocalyptic number.

It is an amenable number.

28356781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28356781 is an equidigital number, since it uses as much as digits as its factorization.

28356781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 80640, while the sum is 40.

The square root of 28356781 is about 5325.1085434947. The cubic root of 28356781 is about 304.9432161600.

The spelling of 28356781 in words is "twenty-eight million, three hundred fifty-six thousand, seven hundred eighty-one".