7851661940 has 12 divisors (see below), whose sum is σ = 16488490116. Its totient is φ = 3140664768.

The previous prime is 7851661931. The next prime is 7851661943. The reversal of 7851661940 is 491661587.

It can be written as a sum of positive squares in 2 ways, for example, as 1696945636 + 6154716304 = 41194^2 + 78452^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7851661943) 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, 196291529 + ... + 196291568.

It is an arithmetic number, because the mean of its divisors is an integer number (1374040843).

Almost surely, 2^7851661940 is an apocalyptic number.

It is an amenable number.

7851661940 is an abundant number, since it is smaller than the sum of its proper divisors (8636828176).

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

7851661940 is a wasteful number, since it uses less digits than its factorization.

7851661940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392583106 (or 392583104 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 47.

The square root of 7851661940 is about 88609.6041070041. The cubic root of 7851661940 is about 1987.5612946828.

The spelling of 7851661940 in words is "seven billion, eight hundred fifty-one million, six hundred sixty-one thousand, nine hundred forty".