665621047 has 12 divisors (see below), whose sum is σ = 833855736. Its totient is φ = 526644720.

The previous prime is 665620993. The next prime is 665621093. The reversal of 665621047 is 740126566.

It is a happy number.

It is not a de Polignac number, because 665621047 - 2¹⁵ = 665588279 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 665620997 and 665621015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665651047) 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, 521829 + ... + 523102.

It is an arithmetic number, because the mean of its divisors is an integer number (69487978).

Almost surely, 2^665621047 is an apocalyptic number.

665621047 is a deficient number, since it is larger than the sum of its proper divisors (168234689).

665621047 is a wasteful number, since it uses less digits than its factorization.

665621047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1044958 (or 1044951 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 37.

The square root of 665621047 is about 25799.6326911838. The cubic root of 665621047 is about 873.1235092950.

The spelling of 665621047 in words is "six hundred sixty-five million, six hundred twenty-one thousand, forty-seven".