8135550721 has 4 divisors (see below), whose sum is σ = 8289051732. Its totient is φ = 7982049712.

The previous prime is 8135550673. The next prime is 8135550733. The reversal of 8135550721 is 1270555318.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5014764225 + 3120786496 = 70815^2 + 55864^2 .

It is a cyclic number.

It is not a de Polignac number, because 8135550721 - 2¹⁹ = 8135026433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8135556721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76750426 + ... + 76750531.

It is an arithmetic number, because the mean of its divisors is an integer number (2072262933).

Almost surely, 2^8135550721 is an apocalyptic number.

It is an amenable number.

8135550721 is a deficient number, since it is larger than the sum of its proper divisors (153501011).

8135550721 is a wasteful number, since it uses less digits than its factorization.

8135550721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153501010.

The product of its (nonzero) digits is 42000, while the sum is 37.

The square root of 8135550721 is about 90197.2877696442. The cubic root of 8135550721 is about 2011.2326886639.

The spelling of 8135550721 in words is "eight billion, one hundred thirty-five million, five hundred fifty thousand, seven hundred twenty-one".