6664029781 has 4 divisors (see below), whose sum is σ = 6844138732. Its totient is φ = 6483920832.

The previous prime is 6664029773. The next prime is 6664029787. The reversal of 6664029781 is 1879204666.

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 6058131556 + 605898225 = 77834^2 + 24615^2 .

It is a cyclic number.

It is not a de Polignac number, because 6664029781 - 2³ = 6664029773 is a prime.

It is a super-2 number, since 2×6664029781² = 88818585844109815922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6664029787) 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, 90054420 + ... + 90054493.

It is an arithmetic number, because the mean of its divisors is an integer number (1711034683).

Almost surely, 2^6664029781 is an apocalyptic number.

It is an amenable number.

6664029781 is a deficient number, since it is larger than the sum of its proper divisors (180108951).

6664029781 is a wasteful number, since it uses less digits than its factorization.

6664029781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180108950.

The product of its (nonzero) digits is 870912, while the sum is 49.

The square root of 6664029781 is about 81633.5089347506. The cubic root of 6664029781 is about 1881.8238845973.

The spelling of 6664029781 in words is "six billion, six hundred sixty-four million, twenty-nine thousand, seven hundred eighty-one".