281997561 has 8 divisors (see below), whose sum is σ = 376512640. Its totient is φ = 187740432.

The previous prime is 281997539. The next prime is 281997589. The reversal of 281997561 is 165799182.

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

It is not a de Polignac number, because 281997561 - 2⁷ = 281997433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 281997561.

It is not an unprimeable number, because it can be changed into a prime (281990561) 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, 61921 + ... + 66318.

It is an arithmetic number, because the mean of its divisors is an integer number (47064080).

Almost surely, 2^281997561 is an apocalyptic number.

It is an amenable number.

281997561 is a deficient number, since it is larger than the sum of its proper divisors (94515079).

281997561 is a wasteful number, since it uses less digits than its factorization.

281997561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128975.

The product of its digits is 272160, while the sum is 48.

The square root of 281997561 is about 16792.7830034214. The cubic root of 281997561 is about 655.7653280486.

The spelling of 281997561 in words is "two hundred eighty-one million, nine hundred ninety-seven thousand, five hundred sixty-one".