661520233 has 16 divisors (see below), whose sum is σ = 736073856. Its totient is φ = 589472640.

The previous prime is 661520219. The next prime is 661520239. The reversal of 661520233 is 332025166.

It is a cyclic number.

It is not a de Polignac number, because 661520233 - 2¹⁷ = 661389161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661520239) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 131635 + ... + 136567.

It is an arithmetic number, because the mean of its divisors is an integer number (46004616).

Almost surely, 2^661520233 is an apocalyptic number.

It is an amenable number.

661520233 is a deficient number, since it is larger than the sum of its proper divisors (74553623).

661520233 is a wasteful number, since it uses less digits than its factorization.

661520233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5184.

The product of its (nonzero) digits is 6480, while the sum is 28.

The square root of 661520233 is about 25720.0356337234. The cubic root of 661520233 is about 871.3267434785.

Adding to 661520233 its reverse (332025166), we get a palindrome (993545399).

The spelling of 661520233 in words is "six hundred sixty-one million, five hundred twenty thousand, two hundred thirty-three".