129542661 has 24 divisors (see below), whose sum is σ = 194843480. Its totient is φ = 82876608.

The previous prime is 129542593. The next prime is 129542663. The reversal of 129542661 is 166245921.

It can be written as a sum of positive squares in 4 ways, for example, as 13549761 + 115992900 = 3681^2 + 10770^2 .

It is not a de Polignac number, because 129542661 - 2¹⁷ = 129411589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129542663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1774521 + ... + 1774593.

Almost surely, 2^129542661 is an apocalyptic number.

It is an amenable number.

129542661 is a deficient number, since it is larger than the sum of its proper divisors (65300819).

129542661 is an frugal number, since it uses more digits than its factorization.

129542661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 113 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 129542661 is about 11381.6809391232. The cubic root of 129542661 is about 505.9849560953.

It can be divided in two parts, 1295 and 42661, that added together give a triangular number (43956 = T₂₉₆).

The spelling of 129542661 in words is "one hundred twenty-nine million, five hundred forty-two thousand, six hundred sixty-one".