665151661 has 4 divisors (see below), whose sum is σ = 679303872. Its totient is φ = 650999452.

The previous prime is 665151647. The next prime is 665151709. The reversal of 665151661 is 166151566.

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 665151661 - 2⁵ = 665151629 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 665151661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665151631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7076035 + ... + 7076128.

It is an arithmetic number, because the mean of its divisors is an integer number (169825968).

Almost surely, 2^665151661 is an apocalyptic number.

It is an amenable number.

665151661 is a deficient number, since it is larger than the sum of its proper divisors (14152211).

665151661 is a wasteful number, since it uses less digits than its factorization.

665151661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14152210.

The product of its digits is 32400, while the sum is 37.

The square root of 665151661 is about 25790.5343294783. The cubic root of 665151661 is about 872.9182231556.

The spelling of 665151661 in words is "six hundred sixty-five million, one hundred fifty-one thousand, six hundred sixty-one".