661544237 has 2 divisors, whose sum is σ = 661544238. Its totient is φ = 661544236.

The previous prime is 661544227. The next prime is 661544249. The reversal of 661544237 is 732445166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 396049801 + 265494436 = 19901^2 + 16294^2 .

It is a cyclic number.

It is not a de Polignac number, because 661544237 - 2⁶ = 661544173 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661544237.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661544227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330772118 + 330772119.

It is an arithmetic number, because the mean of its divisors is an integer number (330772119).

Almost surely, 2^661544237 is an apocalyptic number.

It is an amenable number.

661544237 is a deficient number, since it is larger than the sum of its proper divisors (1).

661544237 is an equidigital number, since it uses as much as digits as its factorization.

661544237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 38.

The square root of 661544237 is about 25720.5022695903. The cubic root of 661544237 is about 871.3372823722.

The spelling of 661544237 in words is "six hundred sixty-one million, five hundred forty-four thousand, two hundred thirty-seven".