661505418 has 24 divisors (see below), whose sum is σ = 1638013728. Its totient is φ = 189001512.

The previous prime is 661505417. The next prime is 661505423. The reversal of 661505418 is 814505166.

661505418 is a `hidden beast` number, since 6 + 61 + 50 + 541 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (661505417) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2624896 + ... + 2625147.

It is an arithmetic number, because the mean of its divisors is an integer number (68250572).

Almost surely, 2^661505418 is an apocalyptic number.

661505418 is an abundant number, since it is smaller than the sum of its proper divisors (976508310).

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

661505418 is a wasteful number, since it uses less digits than its factorization.

661505418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5250058 (or 5250055 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 661505418 is about 25719.7476270666. The cubic root of 661505418 is about 871.3202388641.

The spelling of 661505418 in words is "six hundred sixty-one million, five hundred five thousand, four hundred eighteen".