6448737781 has 4 divisors (see below), whose sum is σ = 6449695564. Its totient is φ = 6447780000.

The previous prime is 6448737773. The next prime is 6448737797. The reversal of 6448737781 is 1877378446.

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 858783025 + 5589954756 = 29305^2 + 74766^2 .

It is a cyclic number.

It is not a de Polignac number, because 6448737781 - 2³ = 6448737773 is a prime.

It is a super-2 number, since 2×6448737781² = 83172437936193607922, 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 (6448737761) 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, 468720 + ... + 482281.

It is an arithmetic number, because the mean of its divisors is an integer number (1612423891).

Almost surely, 2^6448737781 is an apocalyptic number.

It is an amenable number.

6448737781 is a deficient number, since it is larger than the sum of its proper divisors (957783).

6448737781 is an equidigital number, since it uses as much as digits as its factorization.

6448737781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 957782.

The product of its digits is 6322176, while the sum is 55.

The square root of 6448737781 is about 80304.0334043067. The cubic root of 6448737781 is about 1861.3365524583.

The spelling of 6448737781 in words is "six billion, four hundred forty-eight million, seven hundred thirty-seven thousand, seven hundred eighty-one".