7138816721 has 8 divisors (see below), whose sum is σ = 7314483624. Its totient is φ = 6963223680.

The previous prime is 7138816693. The next prime is 7138816723. The reversal of 7138816721 is 1276188317.

It can be written as a sum of positive squares in 4 ways, for example, as 3414766096 + 3724050625 = 58436^2 + 61025^2 .

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 7138816721 - 2¹⁴ = 7138800337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7138816723) 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, 212171 + ... + 243503.

It is an arithmetic number, because the mean of its divisors is an integer number (914310453).

Almost surely, 2^7138816721 is an apocalyptic number.

It is an amenable number.

7138816721 is a deficient number, since it is larger than the sum of its proper divisors (175666903).

7138816721 is a wasteful number, since it uses less digits than its factorization.

7138816721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36931.

The product of its digits is 112896, while the sum is 44.

The square root of 7138816721 is about 84491.5186335291. The cubic root of 7138816721 is about 1925.4935909511.

The spelling of 7138816721 in words is "seven billion, one hundred thirty-eight million, eight hundred sixteen thousand, seven hundred twenty-one".