667653532781 has 2 divisors, whose sum is σ = 667653532782. Its totient is φ = 667653532780.

The previous prime is 667653532771. The next prime is 667653532817. The reversal of 667653532781 is 187235356766.

667653532781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with next prime (667653532817) 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., 593348224681 + 74305308100 = 770291^2 + 272590^2 .

It is a cyclic number.

It is not a de Polignac number, because 667653532781 - 2¹⁰ = 667653531757 is a prime.

It is a super-2 number, since 2×667653532781² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 667653532781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (667653532771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333826766390 + 333826766391.

It is an arithmetic number, because the mean of its divisors is an integer number (333826766391).

Almost surely, 2^667653532781 is an apocalyptic number.

It is an amenable number.

667653532781 is a deficient number, since it is larger than the sum of its proper divisors (1).

667653532781 is an equidigital number, since it uses as much as digits as its factorization.

667653532781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38102400, while the sum is 59.

The spelling of 667653532781 in words is "six hundred sixty-seven billion, six hundred fifty-three million, five hundred thirty-two thousand, seven hundred eighty-one".