28512501781 has 2 divisors, whose sum is σ = 28512501782. Its totient is φ = 28512501780.

The previous prime is 28512501769. The next prime is 28512501799. The reversal of 28512501781 is 18710521582.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28044861156 + 467640625 = 167466^2 + 21625^2 .

It is a cyclic number.

It is not a de Polignac number, because 28512501781 - 2¹¹ = 28512499733 is a prime.

It is a super-2 number, since 2×28512501781² (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 (28512501481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14256250890 + 14256250891.

It is an arithmetic number, because the mean of its divisors is an integer number (14256250891).

Almost surely, 2^28512501781 is an apocalyptic number.

It is an amenable number.

28512501781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28512501781 is an equidigital number, since it uses as much as digits as its factorization.

28512501781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 44800, while the sum is 40.

The spelling of 28512501781 in words is "twenty-eight billion, five hundred twelve million, five hundred one thousand, seven hundred eighty-one".