664001261 has 8 divisors (see below), whose sum is σ = 827845824. Its totient is φ = 517403520.

The previous prime is 664001257. The next prime is 664001263. The reversal of 664001261 is 162100466.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 664001261 - 2² = 664001257 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 664001261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664001263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4311620 + ... + 4311773.

It is an arithmetic number, because the mean of its divisors is an integer number (103480728).

Almost surely, 2^664001261 is an apocalyptic number.

It is an amenable number.

664001261 is a deficient number, since it is larger than the sum of its proper divisors (163844563).

664001261 is a wasteful number, since it uses less digits than its factorization.

664001261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8623411.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 664001261 is about 25768.2219215840. The cubic root of 664001261 is about 872.4146865568.

The spelling of 664001261 in words is "six hundred sixty-four million, one thousand, two hundred sixty-one".