128971761 has 4 divisors (see below), whose sum is σ = 171962352. Its totient is φ = 85981172.

The previous prime is 128971747. The next prime is 128971771. The reversal of 128971761 is 167179821.

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: 167179821 = 3 ⋅55726607.

It is a cyclic number.

It is not a de Polignac number, because 128971761 - 2⁶ = 128971697 is a prime.

It is a super-2 number, since 2×128971761² = 33267430270882242, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (128971721) 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, 21495291 + ... + 21495296.

It is an arithmetic number, because the mean of its divisors is an integer number (42990588).

Almost surely, 2^128971761 is an apocalyptic number.

It is an amenable number.

128971761 is a deficient number, since it is larger than the sum of its proper divisors (42990591).

128971761 is an equidigital number, since it uses as much as digits as its factorization.

128971761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42990590.

The product of its digits is 42336, while the sum is 42.

The square root of 128971761 is about 11356.5734709022. The cubic root of 128971761 is about 505.2405624450.

The spelling of 128971761 in words is "one hundred twenty-eight million, nine hundred seventy-one thousand, seven hundred sixty-one".