28138766531 has 2 divisors, whose sum is σ = 28138766532. Its totient is φ = 28138766530.

The previous prime is 28138766477. The next prime is 28138766561. The reversal of 28138766531 is 13566783182.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28138766531 is a prime.

It is a super-2 number, since 2×28138766531² (a number of 22 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28138766531.

It is not a weakly prime, because it can be changed into another prime (28138766561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14069383265 + 14069383266.

It is an arithmetic number, because the mean of its divisors is an integer number (14069383266).

Almost surely, 2^28138766531 is an apocalyptic number.

28138766531 is a deficient number, since it is larger than the sum of its proper divisors (1).

28138766531 is an equidigital number, since it uses as much as digits as its factorization.

28138766531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1451520, while the sum is 50.

The spelling of 28138766531 in words is "twenty-eight billion, one hundred thirty-eight million, seven hundred sixty-six thousand, five hundred thirty-one".