6400781081 has 8 divisors (see below), whose sum is σ = 6622420680. Its totient is φ = 6179203072.

The previous prime is 6400781069. The next prime is 6400781089. The reversal of 6400781081 is 1801870046.

It can be written as a sum of positive squares in 4 ways, for example, as 1076889856 + 5323891225 = 32816^2 + 72965^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 6400781081 - 2¹⁴ = 6400764697 is a prime.

It is a super-2 number, since 2×6400781081² = 81939996893775057122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6400781089) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 320711 + ... + 340083.

It is an arithmetic number, because the mean of its divisors is an integer number (827802585).

Almost surely, 2^6400781081 is an apocalyptic number.

It is an amenable number.

6400781081 is a deficient number, since it is larger than the sum of its proper divisors (221639599).

6400781081 is a wasteful number, since it uses less digits than its factorization.

6400781081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30795.

The product of its (nonzero) digits is 10752, while the sum is 35.

The square root of 6400781081 is about 80004.8816073119. The cubic root of 6400781081 is about 1856.7110607236.

The spelling of 6400781081 in words is "six billion, four hundred million, seven hundred eighty-one thousand, eighty-one".