7851345921 has 6 divisors (see below), whose sum is σ = 11340833010. Its totient is φ = 5234230608.

The previous prime is 7851345899. The next prime is 7851345923. The reversal of 7851345921 is 1295431587.

7851345921 is a `hidden beast` number, since 7 + 8 + 51 + 3 + 4 + 592 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7840217025 + 11128896 = 88545^2 + 3336^2 .

It is not a de Polignac number, because 7851345921 - 2²⁵ = 7817791489 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (7851345923) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 436185876 + ... + 436185893.

It is an arithmetic number, because the mean of its divisors is an integer number (1890138835).

Almost surely, 2^7851345921 is an apocalyptic number.

It is an amenable number.

7851345921 is a deficient number, since it is larger than the sum of its proper divisors (3489487089).

7851345921 is a wasteful number, since it uses less digits than its factorization.

7851345921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 872371775 (or 872371772 counting only the distinct ones).

The product of its digits is 302400, while the sum is 45.

The square root of 7851345921 is about 88607.8208794235. The cubic root of 7851345921 is about 1987.5346287547.

The spelling of 7851345921 in words is "seven billion, eight hundred fifty-one million, three hundred forty-five thousand, nine hundred twenty-one".