661539318 has 32 divisors (see below), whose sum is σ = 1489923072. Its totient is φ = 193999200.

The previous prime is 661539313. The next prime is 661539323. The reversal of 661539318 is 813935166.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (661539313) and next prime (661539323).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 661539318.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661539313) 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, 159621 + ... + 163712.

It is an arithmetic number, because the mean of its divisors is an integer number (46560096).

Almost surely, 2^661539318 is an apocalyptic number.

661539318 is an abundant number, since it is smaller than the sum of its proper divisors (828383754).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661539318 is a wasteful number, since it uses less digits than its factorization.

661539318 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323380.

The product of its digits is 116640, while the sum is 42.

The square root of 661539318 is about 25720.4066453079. The cubic root of 661539318 is about 871.3351227188.

The spelling of 661539318 in words is "six hundred sixty-one million, five hundred thirty-nine thousand, three hundred eighteen".