281981991 has 8 divisors (see below), whose sum is σ = 381126640. Its totient is φ = 185412672.

The previous prime is 281981989. The next prime is 281982061. The reversal of 281981991 is 199189182.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 281981991 - 2¹ = 281981989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 281981991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (281981971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 643576 + ... + 644013.

It is an arithmetic number, because the mean of its divisors is an integer number (47640830).

Almost surely, 2^281981991 is an apocalyptic number.

281981991 is a deficient number, since it is larger than the sum of its proper divisors (99144649).

281981991 is a wasteful number, since it uses less digits than its factorization.

281981991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1287665.

The product of its digits is 93312, while the sum is 48.

The square root of 281981991 is about 16792.3194050137. The cubic root of 281981991 is about 655.7532588495.

The spelling of 281981991 in words is "two hundred eighty-one million, nine hundred eighty-one thousand, nine hundred ninety-one".