7921390838 has 16 divisors (see below), whose sum is σ = 12063665664. Its totient is φ = 3900210600.

The previous prime is 7921390837. The next prime is 7921390849. The reversal of 7921390838 is 8380931297.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7921390837) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 447863 + ... + 465213.

It is an arithmetic number, because the mean of its divisors is an integer number (753979104).

Almost surely, 2^7921390838 is an apocalyptic number.

7921390838 is a deficient number, since it is larger than the sum of its proper divisors (4142274826).

7921390838 is a wasteful number, since it uses less digits than its factorization.

7921390838 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20827.

The product of its (nonzero) digits is 653184, while the sum is 50.

The square root of 7921390838 is about 89002.1956920165. The cubic root of 7921390838 is about 1993.4276623469.

The spelling of 7921390838 in words is "seven billion, nine hundred twenty-one million, three hundred ninety thousand, eight hundred thirty-eight".