28747981 has 2 divisors, whose sum is σ = 28747982. Its totient is φ = 28747980.

The previous prime is 28747949. The next prime is 28747993. The reversal of 28747981 is 18974782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28185481 + 562500 = 5309^2 + 750^2 .

It is a cyclic number.

It is not a de Polignac number, because 28747981 - 2⁵ = 28747949 is a prime.

It is a super-2 number, since 2×28747981² = 1652892823152722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28747921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14373990 + 14373991.

It is an arithmetic number, because the mean of its divisors is an integer number (14373991).

Almost surely, 2^28747981 is an apocalyptic number.

It is an amenable number.

28747981 is a deficient number, since it is larger than the sum of its proper divisors (1).

28747981 is an equidigital number, since it uses as much as digits as its factorization.

28747981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 46.

The square root of 28747981 is about 5361.7143713555. The cubic root of 28747981 is about 306.3391124266.

The spelling of 28747981 in words is "twenty-eight million, seven hundred forty-seven thousand, nine hundred eighty-one".