28306981 has 2 divisors, whose sum is σ = 28306982. Its totient is φ = 28306980.

The previous prime is 28306969. The next prime is 28307003. The reversal of 28306981 is 18960382.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27720225 + 586756 = 5265^2 + 766^2 .

It is a cyclic number.

It is not a de Polignac number, because 28306981 - 2¹¹ = 28304933 is a prime.

It is a super-2 number, since 2×28306981² = 1602570346668722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28306981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28306931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14153490 + 14153491.

It is an arithmetic number, because the mean of its divisors is an integer number (14153491).

Almost surely, 2^28306981 is an apocalyptic number.

It is an amenable number.

28306981 is a deficient number, since it is larger than the sum of its proper divisors (1).

28306981 is an equidigital number, since it uses as much as digits as its factorization.

28306981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 28306981 is about 5320.4305276923. The cubic root of 28306981 is about 304.7645984389.

The spelling of 28306981 in words is "twenty-eight million, three hundred six thousand, nine hundred eighty-one".