664727261 has 4 divisors (see below), whose sum is σ = 725157024. Its totient is φ = 604297500.

The previous prime is 664727257. The next prime is 664727263. The reversal of 664727261 is 162727466.

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 664727261 - 2² = 664727257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664727263) 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, 30214865 + ... + 30214886.

It is an arithmetic number, because the mean of its divisors is an integer number (181289256).

Almost surely, 2^664727261 is an apocalyptic number.

It is an amenable number.

664727261 is a deficient number, since it is larger than the sum of its proper divisors (60429763).

664727261 is a wasteful number, since it uses less digits than its factorization.

664727261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60429762.

The product of its digits is 169344, while the sum is 41.

The square root of 664727261 is about 25782.3051917395. The cubic root of 664727261 is about 872.7325285060.

The spelling of 664727261 in words is "six hundred sixty-four million, seven hundred twenty-seven thousand, two hundred sixty-one".