128249961 has 16 divisors (see below), whose sum is σ = 195696000. Its totient is φ = 73185408.

The previous prime is 128249959. The next prime is 128249987. The reversal of 128249961 is 169942821.

It is not a de Polignac number, because 128249961 - 2¹ = 128249959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (128249161) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13215 + ... + 20763.

It is an arithmetic number, because the mean of its divisors is an integer number (12231000).

Almost surely, 2^128249961 is an apocalyptic number.

It is an amenable number.

128249961 is a deficient number, since it is larger than the sum of its proper divisors (67446039).

128249961 is an equidigital number, since it uses as much as digits as its factorization.

128249961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8368.

The product of its digits is 62208, while the sum is 42.

The square root of 128249961 is about 11324.7499310139. The cubic root of 128249961 is about 504.2962599021.

The spelling of 128249961 in words is "one hundred twenty-eight million, two hundred forty-nine thousand, nine hundred sixty-one".