661320613 has 8 divisors (see below), whose sum is σ = 691297280. Its totient is φ = 631884240.

The previous prime is 661320599. The next prime is 661320637. The reversal of 661320613 is 316023166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661320613 - 2¹⁷ = 661189541 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 (661321613) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 132570 + ... + 137467.

It is an arithmetic number, because the mean of its divisors is an integer number (86412160).

Almost surely, 2^661320613 is an apocalyptic number.

It is an amenable number.

661320613 is a deficient number, since it is larger than the sum of its proper divisors (29976667).

661320613 is a wasteful number, since it uses less digits than its factorization.

661320613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270147.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 661320613 is about 25716.1547086651. The cubic root of 661320613 is about 871.2390909603.

Adding to 661320613 its reverse (316023166), we get a palindrome (977343779).

The spelling of 661320613 in words is "six hundred sixty-one million, three hundred twenty thousand, six hundred thirteen".