661597247 has 4 divisors (see below), whose sum is σ = 661957296. Its totient is φ = 661237200.

The previous prime is 661597243. The next prime is 661597301. The reversal of 661597247 is 742795166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661597247 - 2² = 661597243 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 (661597243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 177254 + ... + 180947.

It is an arithmetic number, because the mean of its divisors is an integer number (165489324).

Almost surely, 2^661597247 is an apocalyptic number.

661597247 is a deficient number, since it is larger than the sum of its proper divisors (360049).

661597247 is a wasteful number, since it uses less digits than its factorization.

661597247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360048.

The product of its digits is 635040, while the sum is 47.

The square root of 661597247 is about 25721.5327498188. The cubic root of 661597247 is about 871.3605553715.

The spelling of 661597247 in words is "six hundred sixty-one million, five hundred ninety-seven thousand, two hundred forty-seven".