666661500 has 72 divisors (see below), whose sum is σ = 2103109008. Its totient is φ = 177775200.

The previous prime is 666661469. The next prime is 666661519. The reversal of 666661500 is 5166666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 69574 + ... + 78573.

Almost surely, 2^666661500 is an apocalyptic number.

666661500 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

666661500 is an abundant number, since it is smaller than the sum of its proper divisors (1436447508).

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

666661500 is a wasteful number, since it uses less digits than its factorization.

666661500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148172 (or 148157 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The square root of 666661500 is about 25819.7889224525. The cubic root of 666661500 is about 873.5782079809.

The spelling of 666661500 in words is "six hundred sixty-six million, six hundred sixty-one thousand, five hundred".