281978993 has 4 divisors (see below), whose sum is σ = 288536688. Its totient is φ = 275421300.

The previous prime is 281978987. The next prime is 281979001. The reversal of 281978993 is 399879182.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 281978993 - 2⁸ = 281978737 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (281978933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3278783 + ... + 3278868.

It is an arithmetic number, because the mean of its divisors is an integer number (72134172).

Almost surely, 2^281978993 is an apocalyptic number.

It is an amenable number.

281978993 is a deficient number, since it is larger than the sum of its proper divisors (6557695).

281978993 is an equidigital number, since it uses as much as digits as its factorization.

281978993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6557694.

The product of its digits is 1959552, while the sum is 56.

The square root of 281978993 is about 16792.2301377750. The cubic root of 281978993 is about 655.7509348770.

The spelling of 281978993 in words is "two hundred eighty-one million, nine hundred seventy-eight thousand, nine hundred ninety-three".