661667629 has 6 divisors (see below), whose sum is σ = 769695054. Its totient is φ = 567143640.

The previous prime is 661667623. The next prime is 661667641. The reversal of 661667629 is 926766166.

It can be written as a sum of positive squares in only one way, i.e., 466646404 + 195021225 = 21602^2 + 13965^2 .

It is not a de Polignac number, because 661667629 - 2¹⁹ = 661143341 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49), and also a Moran number because the ratio is a prime number: 13503421 = 661667629 / (6 + 6 + 1 + 6 + 6 + 7 + 6 + 2 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661667623) 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 5 ways as a sum of consecutive naturals, for example, 6751662 + ... + 6751759.

It is an arithmetic number, because the mean of its divisors is an integer number (128282509).

Almost surely, 2^661667629 is an apocalyptic number.

It is an amenable number.

661667629 is a deficient number, since it is larger than the sum of its proper divisors (108027425).

661667629 is a wasteful number, since it uses less digits than its factorization.

661667629 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13503435 (or 13503428 counting only the distinct ones).

The product of its digits is 979776, while the sum is 49.

The square root of 661667629 is about 25722.9008667374. The cubic root of 661667629 is about 871.3914532852.

The spelling of 661667629 in words is "six hundred sixty-one million, six hundred sixty-seven thousand, six hundred twenty-nine".