661478429 has 4 divisors (see below), whose sum is σ = 684288060. Its totient is φ = 638668800.

The previous prime is 661478359. The next prime is 661478443. The reversal of 661478429 is 924874166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 924874166 = 2 ⋅462437083.

It can be written as a sum of positive squares in 2 ways, for example, as 502970329 + 158508100 = 22427^2 + 12590^2 .

It is a cyclic number.

It is not a de Polignac number, because 661478429 - 2¹⁶ = 661412893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661478479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11404772 + ... + 11404829.

It is an arithmetic number, because the mean of its divisors is an integer number (171072015).

Almost surely, 2^661478429 is an apocalyptic number.

It is an amenable number.

661478429 is a deficient number, since it is larger than the sum of its proper divisors (22809631).

661478429 is a wasteful number, since it uses less digits than its factorization.

661478429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22809630.

The product of its digits is 580608, while the sum is 47.

The square root of 661478429 is about 25719.2229470488. Note that the first 3 decimals coincide. The cubic root of 661478429 is about 871.3083889326.

The spelling of 661478429 in words is "six hundred sixty-one million, four hundred seventy-eight thousand, four hundred twenty-nine".