2765139721 has 8 divisors (see below), whose sum is σ = 2800464264. Its totient is φ = 2729971200.

The previous prime is 2765139697. The next prime is 2765139731. The reversal of 2765139721 is 1279315672.

It can be written as a sum of positive squares in 4 ways, for example, as 541074121 + 2224065600 = 23261^2 + 47160^2 .

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 2765139721 - 2²⁵ = 2731585289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2765139731) 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, 3126 + ... + 74431.

It is an arithmetic number, because the mean of its divisors is an integer number (350058033).

Almost surely, 2^2765139721 is an apocalyptic number.

It is an amenable number.

2765139721 is a deficient number, since it is larger than the sum of its proper divisors (35324543).

2765139721 is a wasteful number, since it uses less digits than its factorization.

2765139721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78011.

The product of its digits is 158760, while the sum is 43.

The square root of 2765139721 is about 52584.5958527780. The cubic root of 2765139721 is about 1403.5859975336.

The spelling of 2765139721 in words is "two billion, seven hundred sixty-five million, one hundred thirty-nine thousand, seven hundred twenty-one".