661615597 has 4 divisors (see below), whose sum is σ = 661671360. Its totient is φ = 661559836.

The previous prime is 661615573. The next prime is 661615621. The reversal of 661615597 is 795516166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 795516166 = 2 ⋅397758083.

It is an interprime number because it is at equal distance from previous prime (661615573) and next prime (661615621).

It is a cyclic number.

It is not a de Polignac number, because 661615597 - 2¹¹ = 661613549 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 (661615567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2197 + ... + 36442.

It is an arithmetic number, because the mean of its divisors is an integer number (165417840).

Almost surely, 2^661615597 is an apocalyptic number.

It is an amenable number.

661615597 is a deficient number, since it is larger than the sum of its proper divisors (55763).

661615597 is a wasteful number, since it uses less digits than its factorization.

661615597 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55762.

The product of its digits is 340200, while the sum is 46.

The square root of 661615597 is about 25721.8894523711. The cubic root of 661615597 is about 871.3686112889.

The spelling of 661615597 in words is "six hundred sixty-one million, six hundred fifteen thousand, five hundred ninety-seven".