664787083781 has 4 divisors (see below), whose sum is σ = 667258411500. Its totient is φ = 662315756064.

The previous prime is 664787083759. The next prime is 664787083789. The reversal of 664787083781 is 187380787466.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28134694756 + 636652389025 = 167734^2 + 797905^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664787083781 is a prime.

It is a super-2 number, since 2×664787083781² (a number of 24 digits) contains 22 as substring.

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 (664787083789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1235663456 + ... + 1235663993.

It is an arithmetic number, because the mean of its divisors is an integer number (166814602875).

Almost surely, 2^664787083781 is an apocalyptic number.

It is an amenable number.

664787083781 is a deficient number, since it is larger than the sum of its proper divisors (2471327719).

664787083781 is a wasteful number, since it uses less digits than its factorization.

664787083781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2471327718.

The product of its (nonzero) digits is 75866112, while the sum is 65.

The spelling of 664787083781 in words is "six hundred sixty-four billion, seven hundred eighty-seven million, eighty-three thousand, seven hundred eighty-one".