664778413 has 6 divisors (see below), whose sum is σ = 716015342. Its totient is φ = 613555800.

The previous prime is 664778363. The next prime is 664778423. The reversal of 664778413 is 314877466.

It can be written as a sum of positive squares in only one way, i.e., 460231209 + 204547204 = 21453^2 + 14302^2 .

It is not a de Polignac number, because 664778413 - 2²⁵ = 631223981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664778423) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 89388 + ... + 96538.

Almost surely, 2^664778413 is an apocalyptic number.

It is an amenable number.

664778413 is a deficient number, since it is larger than the sum of its proper divisors (51236929).

664778413 is an frugal number, since it uses more digits than its factorization.

664778413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14315 (or 7164 counting only the distinct ones).

The product of its digits is 677376, while the sum is 46.

The square root of 664778413 is about 25783.2971708430. The cubic root of 664778413 is about 872.7549140626.

The spelling of 664778413 in words is "six hundred sixty-four million, seven hundred seventy-eight thousand, four hundred thirteen".