281138722921 has 4 divisors (see below), whose sum is σ = 321301397632. Its totient is φ = 240976048212.

The previous prime is 281138722919. The next prime is 281138722927. The reversal of 281138722921 is 129227831182.

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 281138722921 - 2¹ = 281138722919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (281138722927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20081337345 + ... + 20081337358.

It is an arithmetic number, because the mean of its divisors is an integer number (80325349408).

Almost surely, 2^281138722921 is an apocalyptic number.

It is an amenable number.

281138722921 is a deficient number, since it is larger than the sum of its proper divisors (40162674711).

281138722921 is an equidigital number, since it uses as much as digits as its factorization.

281138722921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40162674710.

The product of its digits is 193536, while the sum is 46.

The spelling of 281138722921 in words is "two hundred eighty-one billion, one hundred thirty-eight million, seven hundred twenty-two thousand, nine hundred twenty-one".