155664205681 has 2 divisors, whose sum is σ = 155664205682. Its totient is φ = 155664205680.

The previous prime is 155664205661. The next prime is 155664205717. The reversal of 155664205681 is 186502466551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 151492208400 + 4171997281 = 389220^2 + 64591^2 .

It is a cyclic number.

It is not a de Polignac number, because 155664205681 - 2⁷ = 155664205553 is a prime.

It is a super-2 number, since 2×155664205681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (155664205661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77832102840 + 77832102841.

It is an arithmetic number, because the mean of its divisors is an integer number (77832102841).

Almost surely, 2^155664205681 is an apocalyptic number.

It is an amenable number.

155664205681 is a deficient number, since it is larger than the sum of its proper divisors (1).

155664205681 is an equidigital number, since it uses as much as digits as its factorization.

155664205681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728000, while the sum is 49.

The spelling of 155664205681 in words is "one hundred fifty-five billion, six hundred sixty-four million, two hundred five thousand, six hundred eighty-one".