720664665 has 32 divisors (see below), whose sum is σ = 1318941696. Its totient is φ = 329158080.

The previous prime is 720664643. The next prime is 720664669. The reversal of 720664665 is 566466027.

It is not a de Polignac number, because 720664665 - 2¹² = 720660569 is a prime.

It is not an unprimeable number, because it can be changed into a prime (720664669) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 158514 + ... + 162996.

It is an arithmetic number, because the mean of its divisors is an integer number (41216928).

Almost surely, 2^720664665 is an apocalyptic number.

It is an amenable number.

720664665 is a deficient number, since it is larger than the sum of its proper divisors (598277031).

720664665 is a wasteful number, since it uses less digits than its factorization.

720664665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6029.

The product of its (nonzero) digits is 362880, while the sum is 42.

The square root of 720664665 is about 26845.1981739752. The cubic root of 720664665 is about 896.5566638285.

The spelling of 720664665 in words is "seven hundred twenty million, six hundred sixty-four thousand, six hundred sixty-five".