28646513981 has 2 divisors, whose sum is σ = 28646513982. Its totient is φ = 28646513980.

The previous prime is 28646513933. The next prime is 28646514047. The reversal of 28646513981 is 18931564682.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25483013956 + 3163500025 = 159634^2 + 56245^2 .

It is a cyclic number.

It is not a de Polignac number, because 28646513981 - 2²⁶ = 28579405117 is a prime.

It is a super-2 number, since 2×28646513981² (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 (28646513381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14323256990 + 14323256991.

It is an arithmetic number, because the mean of its divisors is an integer number (14323256991).

Almost surely, 2^28646513981 is an apocalyptic number.

It is an amenable number.

28646513981 is a deficient number, since it is larger than the sum of its proper divisors (1).

28646513981 is an equidigital number, since it uses as much as digits as its factorization.

28646513981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2488320, while the sum is 53.

The spelling of 28646513981 in words is "twenty-eight billion, six hundred forty-six million, five hundred thirteen thousand, nine hundred eighty-one".