7921390840 has 48 divisors (see below), whose sum is σ = 19590724440. Its totient is φ = 2880504000.

The previous prime is 7921390837. The next prime is 7921390849. The reversal of 7921390840 is 480931297.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7921390849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 813486 + ... + 823165.

Almost surely, 2^7921390840 is an apocalyptic number.

It is an amenable number.

7921390840 is an abundant number, since it is smaller than the sum of its proper divisors (11669333600).

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

7921390840 is a wasteful number, since it uses less digits than its factorization.

7921390840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1636684 (or 1636669 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 43.

The square root of 7921390840 is about 89002.1957032522. The cubic root of 7921390840 is about 1993.4276625147.

The spelling of 7921390840 in words is "seven billion, nine hundred twenty-one million, three hundred ninety thousand, eight hundred forty".