128124721 has 2 divisors, whose sum is σ = 128124722. Its totient is φ = 128124720.

The previous prime is 128124677. The next prime is 128124727. The reversal of 128124721 is 127421821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121550625 + 6574096 = 11025^2 + 2564^2 .

It is a cyclic number.

It is not a de Polignac number, because 128124721 - 2⁷ = 128124593 is a prime.

It is a super-3 number, since 3×128124721³ (a number of 25 digits) contains 333 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128124721.

It is not a weakly prime, because it can be changed into another prime (128124727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64062360 + 64062361.

It is an arithmetic number, because the mean of its divisors is an integer number (64062361).

Almost surely, 2^128124721 is an apocalyptic number.

It is an amenable number.

128124721 is a deficient number, since it is larger than the sum of its proper divisors (1).

128124721 is an equidigital number, since it uses as much as digits as its factorization.

128124721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1792, while the sum is 28.

The square root of 128124721 is about 11319.2190985068. The cubic root of 128124721 is about 504.1320528779.

The spelling of 128124721 in words is "one hundred twenty-eight million, one hundred twenty-four thousand, seven hundred twenty-one".