6445131381 has 12 divisors (see below), whose sum is σ = 10025760108. Its totient is φ = 3966234624.

The previous prime is 6445131349. The next prime is 6445131439. The reversal of 6445131381 is 1831315446.

6445131381 is a `hidden beast` number, since 6 + 4 + 4 + 513 + 138 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 429732900 + 6015398481 = 20730^2 + 77559^2 .

It is not a de Polignac number, because 6445131381 - 2⁵ = 6445131349 is a prime.

It is a super-2 number, since 2×6445131381² = 83079437036701934322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6445131311) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27543180 + ... + 27543413.

It is an arithmetic number, because the mean of its divisors is an integer number (835480009).

Almost surely, 2^6445131381 is an apocalyptic number.

It is an amenable number.

6445131381 is a deficient number, since it is larger than the sum of its proper divisors (3580628727).

6445131381 is a wasteful number, since it uses less digits than its factorization.

6445131381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55086612 (or 55086609 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 6445131381 is about 80281.5756011303. The cubic root of 6445131381 is about 1860.9895090469.

The spelling of 6445131381 in words is "six billion, four hundred forty-five million, one hundred thirty-one thousand, three hundred eighty-one".