661185321 has 4 divisors (see below), whose sum is σ = 881580432. Its totient is φ = 440790212.

The previous prime is 661185319. The next prime is 661185323. The reversal of 661185321 is 123581166.

661185321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is an interprime number because it is at equal distance from previous prime (661185319) and next prime (661185323).

It is a cyclic number.

It is not a de Polignac number, because 661185321 - 2¹ = 661185319 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661185323) 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, 110197551 + ... + 110197556.

It is an arithmetic number, because the mean of its divisors is an integer number (220395108).

Almost surely, 2^661185321 is an apocalyptic number.

It is an amenable number.

661185321 is a deficient number, since it is larger than the sum of its proper divisors (220395111).

661185321 is a wasteful number, since it uses less digits than its factorization.

661185321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220395110.

The product of its digits is 8640, while the sum is 33.

The square root of 661185321 is about 25713.5240875303. The cubic root of 661185321 is about 871.1796746370.

The spelling of 661185321 in words is "six hundred sixty-one million, one hundred eighty-five thousand, three hundred twenty-one".