123128651 has 4 divisors (see below), whose sum is σ = 125992152. Its totient is φ = 120265152.

The previous prime is 123128641. The next prime is 123128657. The reversal of 123128651 is 156821321.

123128651 is nontrivially palindromic in base 9.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 156821321 = 71 ⋅2208751.

It is a de Polignac number, because none of the positive numbers 2^k-123128651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (123128657) 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, 1431686 + ... + 1431771.

It is an arithmetic number, because the mean of its divisors is an integer number (31498038).

Almost surely, 2^123128651 is an apocalyptic number.

123128651 is a deficient number, since it is larger than the sum of its proper divisors (2863501).

123128651 is an equidigital number, since it uses as much as digits as its factorization.

123128651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2863500.

The product of its digits is 2880, while the sum is 29.

The square root of 123128651 is about 11096.3350255839. The cubic root of 123128651 is about 497.4923120282.

Adding to 123128651 its reverse (156821321), we get a palindrome (279949972).

The spelling of 123128651 in words is "one hundred twenty-three million, one hundred twenty-eight thousand, six hundred fifty-one".