7138891821 has 8 divisors (see below), whose sum is σ = 10078435584. Its totient is φ = 4479304640.

The previous prime is 7138891817. The next prime is 7138891843. The reversal of 7138891821 is 1281988317.

It is a happy number.

7138891821 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 7138891821 - 2² = 7138891817 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7138891871) 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, 69989085 + ... + 69989186.

It is an arithmetic number, because the mean of its divisors is an integer number (1259804448).

Almost surely, 2^7138891821 is an apocalyptic number.

It is an amenable number.

7138891821 is a deficient number, since it is larger than the sum of its proper divisors (2939543763).

7138891821 is a wasteful number, since it uses less digits than its factorization.

7138891821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139978291.

The product of its digits is 193536, while the sum is 48.

The square root of 7138891821 is about 84491.9630556658. The cubic root of 7138891821 is about 1925.5003429600.

The spelling of 7138891821 in words is "seven billion, one hundred thirty-eight million, eight hundred ninety-one thousand, eight hundred twenty-one".