7905618821 has 4 divisors (see below), whose sum is σ = 7916008044. Its totient is φ = 7895229600.

The previous prime is 7905618767. The next prime is 7905618841. The reversal of 7905618821 is 1288165097.

7905618821 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 62568100 + 7843050721 = 7910^2 + 88561^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7905618821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7905618841) 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, 5193470 + ... + 5194991.

It is an arithmetic number, because the mean of its divisors is an integer number (1979002011).

Almost surely, 2^7905618821 is an apocalyptic number.

It is an amenable number.

7905618821 is a deficient number, since it is larger than the sum of its proper divisors (10389223).

7905618821 is a wasteful number, since it uses less digits than its factorization.

7905618821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10389222.

The product of its (nonzero) digits is 241920, while the sum is 47.

The square root of 7905618821 is about 88913.5468924730. The cubic root of 7905618821 is about 1992.1037675343.

The spelling of 7905618821 in words is "seven billion, nine hundred five million, six hundred eighteen thousand, eight hundred twenty-one".