128334721 has 4 divisors (see below), whose sum is σ = 135089200. Its totient is φ = 121580244.

The previous prime is 128334719. The next prime is 128334737. The reversal of 128334721 is 127433821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 127433821 = 101 ⋅1261721.

It is a cyclic number.

It is not a de Polignac number, because 128334721 - 2¹ = 128334719 is a prime.

It is a super-2 number, since 2×128334721² = 32939601228295682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128334121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3377211 + ... + 3377248.

It is an arithmetic number, because the mean of its divisors is an integer number (33772300).

Almost surely, 2^128334721 is an apocalyptic number.

It is an amenable number.

128334721 is a deficient number, since it is larger than the sum of its proper divisors (6754479).

128334721 is an equidigital number, since it uses as much as digits as its factorization.

128334721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6754478.

The product of its digits is 8064, while the sum is 31.

The square root of 128334721 is about 11328.4915588970. The cubic root of 128334721 is about 504.4073313795.

The spelling of 128334721 in words is "one hundred twenty-eight million, three hundred thirty-four thousand, seven hundred twenty-one".