665639061 has 8 divisors (see below), whose sum is σ = 890894400. Its totient is φ = 442071552.

The previous prime is 665639057. The next prime is 665639071. The reversal of 665639061 is 160936566.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 665639061 - 2² = 665639057 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665639071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 421036 + ... + 422613.

It is an arithmetic number, because the mean of its divisors is an integer number (111361800).

Almost surely, 2^665639061 is an apocalyptic number.

It is an amenable number.

665639061 is a deficient number, since it is larger than the sum of its proper divisors (225255339).

665639061 is a wasteful number, since it uses less digits than its factorization.

665639061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 843915.

The product of its (nonzero) digits is 174960, while the sum is 42.

The square root of 665639061 is about 25799.9818023192. The cubic root of 665639061 is about 873.1313858012.

The spelling of 665639061 in words is "six hundred sixty-five million, six hundred thirty-nine thousand, sixty-one".