6448781381 has 4 divisors (see below), whose sum is σ = 7370035872. Its totient is φ = 5527526892.

The previous prime is 6448781371. The next prime is 6448781399. The reversal of 6448781381 is 1831878446.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6448781381 - 2²² = 6444587077 is a prime.

It is a super-2 number, since 2×6448781381² = 83173562599864534322, 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 (6448781321) 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, 460627235 + ... + 460627248.

It is an arithmetic number, because the mean of its divisors is an integer number (1842508968).

Almost surely, 2^6448781381 is an apocalyptic number.

It is an amenable number.

6448781381 is a deficient number, since it is larger than the sum of its proper divisors (921254491).

6448781381 is an equidigital number, since it uses as much as digits as its factorization.

6448781381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 921254490.

The product of its digits is 1032192, while the sum is 50.

The square root of 6448781381 is about 80304.3048721549. The cubic root of 6448781381 is about 1861.3407472890.

The spelling of 6448781381 in words is "six billion, four hundred forty-eight million, seven hundred eighty-one thousand, three hundred eighty-one".