28890051781 has 2 divisors, whose sum is σ = 28890051782. Its totient is φ = 28890051780.

The previous prime is 28890051763. The next prime is 28890051793. The reversal of 28890051781 is 18715009882.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25907799681 + 2982252100 = 160959^2 + 54610^2 .

It is a cyclic number.

It is not a de Polignac number, because 28890051781 - 2⁹ = 28890051269 is a prime.

It is a super-2 number, since 2×28890051781² (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 (28890051581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14445025890 + 14445025891.

It is an arithmetic number, because the mean of its divisors is an integer number (14445025891).

Almost surely, 2^28890051781 is an apocalyptic number.

It is an amenable number.

28890051781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28890051781 is an equidigital number, since it uses as much as digits as its factorization.

28890051781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 322560, while the sum is 49.

The spelling of 28890051781 in words is "twenty-eight billion, eight hundred ninety million, fifty-one thousand, seven hundred eighty-one".