666661501 has 4 divisors (see below), whose sum is σ = 727267104. Its totient is φ = 606055900.

The previous prime is 666661469. The next prime is 666661519. The reversal of 666661501 is 105166666.

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 a cyclic number.

It is not a de Polignac number, because 666661501 - 2⁵ = 666661469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666661571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30302785 + ... + 30302806.

It is an arithmetic number, because the mean of its divisors is an integer number (181816776).

Almost surely, 2^666661501 is an apocalyptic number.

It is an amenable number.

666661501 is a deficient number, since it is larger than the sum of its proper divisors (60605603).

666661501 is a wasteful number, since it uses less digits than its factorization.

666661501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60605602.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 666661501 is about 25819.7889418175. The cubic root of 666661501 is about 873.5782084177.

The spelling of 666661501 in words is "six hundred sixty-six million, six hundred sixty-one thousand, five hundred one".