7865738721 has 81 divisors (see below), whose sum is σ = 12673815609. Its totient is φ = 4699807488.

The previous prime is 7865738719. The next prime is 7865738723. The reversal of 7865738721 is 1278375687.

The square root of 7865738721 is 88689.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (7865738719) and next prime (7865738723).

It can be written as a sum of positive squares in 4 ways, for example, as 3658919121 + 4206819600 = 60489^2 + 64860^2 .

It is not a de Polignac number, because 7865738721 - 2¹ = 7865738719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7865738723) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 167356120 + ... + 167356166.

Almost surely, 2^7865738721 is an apocalyptic number.

7865738721 is the 88689-th square number.

7865738721 is the 44345-th centered octagonal number.

It is an amenable number.

7865738721 is a deficient number, since it is larger than the sum of its proper divisors (4808076888).

7865738721 is a wasteful number, since it uses less digits than its factorization.

7865738721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208 (or 104 counting only the distinct ones).

The product of its digits is 3951360, while the sum is 54.

The cubic root of 7865738721 is about 1988.7483793028.

The spelling of 7865738721 in words is "seven billion, eight hundred sixty-five million, seven hundred thirty-eight thousand, seven hundred twenty-one".