28233121781 has 2 divisors, whose sum is σ = 28233121782. Its totient is φ = 28233121780.

The previous prime is 28233121751. The next prime is 28233121817. The reversal of 28233121781 is 18712133282.

Together with next prime (28233121817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27050380900 + 1182740881 = 164470^2 + 34391^2 .

It is a cyclic number.

It is not a de Polignac number, because 28233121781 - 2³⁴ = 11053252597 is a prime.

It is a super-2 number, since 2×28233121781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28233121751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14116560890 + 14116560891.

It is an arithmetic number, because the mean of its divisors is an integer number (14116560891).

Almost surely, 2^28233121781 is an apocalyptic number.

It is an amenable number.

28233121781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28233121781 is an equidigital number, since it uses as much as digits as its factorization.

28233121781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32256, while the sum is 38.

The spelling of 28233121781 in words is "twenty-eight billion, two hundred thirty-three million, one hundred twenty-one thousand, seven hundred eighty-one".