129012661 has 4 divisors (see below), whose sum is σ = 129063532. Its totient is φ = 128961792.

The previous prime is 129012659. The next prime is 129012671. The reversal of 129012661 is 166210921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166210921 = 17 ⋅9777113.

It can be written as a sum of positive squares in 2 ways, for example, as 40068900 + 88943761 = 6330^2 + 9431^2 .

It is a cyclic number.

It is not a de Polignac number, because 129012661 - 2¹ = 129012659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129012601) 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, 21420 + ... + 26773.

It is an arithmetic number, because the mean of its divisors is an integer number (32265883).

Almost surely, 2^129012661 is an apocalyptic number.

It is an amenable number.

129012661 is a deficient number, since it is larger than the sum of its proper divisors (50871).

129012661 is an equidigital number, since it uses as much as digits as its factorization.

129012661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50870.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 129012661 is about 11358.3740473714. The cubic root of 129012661 is about 505.2939647165.

The spelling of 129012661 in words is "one hundred twenty-nine million, twelve thousand, six hundred sixty-one".