6851809440 has 240 divisors, whose sum is σ = 27635997312. Its totient is φ = 1566107136.

The previous prime is 6851809361. The next prime is 6851809463. The reversal of 6851809440 is 449081586.

6851809440 is a `hidden beast` number, since 6 + 8 + 518 + 0 + 94 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-2 number, since 2×6851809440² = 93894585204146227200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 52957 + ... + 128483.

Almost surely, 2^6851809440 is an apocalyptic number.

6851809440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6851809440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13817998656).

6851809440 is an abundant number, since it is smaller than the sum of its proper divisors (20784187872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6851809440 is a wasteful number, since it uses less digits than its factorization.

6851809440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75561 (or 75544 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The square root of 6851809440 is about 82775.6572912592. The cubic root of 6851809440 is about 1899.3358195586.

The spelling of 6851809440 in words is "six billion, eight hundred fifty-one million, eight hundred nine thousand, four hundred forty".