128007661 has 2 divisors, whose sum is σ = 128007662. Its totient is φ = 128007660.

The previous prime is 128007619. The next prime is 128007697. The reversal of 128007661 is 166700821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125014761 + 2992900 = 11181^2 + 1730^2 .

It is a cyclic number.

It is not a de Polignac number, because 128007661 - 2¹¹ = 128005613 is a prime.

It is a super-2 number, since 2×128007661² = 32771922549381842, which contains 22 as substring.

It is equal to p_7271455 and since 128007661 and 7271455 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128001661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64003830 + 64003831.

It is an arithmetic number, because the mean of its divisors is an integer number (64003831).

Almost surely, 2^128007661 is an apocalyptic number.

It is an amenable number.

128007661 is a deficient number, since it is larger than the sum of its proper divisors (1).

128007661 is an equidigital number, since it uses as much as digits as its factorization.

128007661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 128007661 is about 11314.0470654846. The cubic root of 128007661 is about 503.9784741898.

The spelling of 128007661 in words is "one hundred twenty-eight million, seven thousand, six hundred sixty-one".