7539321821 has 4 divisors (see below), whose sum is σ = 7541409852. Its totient is φ = 7537233792.

The previous prime is 7539321817. The next prime is 7539321827. The reversal of 7539321821 is 1281239357.

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 1191216196 + 6348105625 = 34514^2 + 79675^2 .

It is a cyclic number.

It is not a de Polignac number, because 7539321821 - 2² = 7539321817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7539321827) 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, 1038590 + ... + 1045823.

It is an arithmetic number, because the mean of its divisors is an integer number (1885352463).

Almost surely, 2^7539321821 is an apocalyptic number.

It is an amenable number.

7539321821 is a deficient number, since it is larger than the sum of its proper divisors (2088031).

7539321821 is a wasteful number, since it uses less digits than its factorization.

7539321821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2088030.

The product of its digits is 90720, while the sum is 41.

The square root of 7539321821 is about 86829.2682279426. The cubic root of 7539321821 is about 1960.8487422473.

The spelling of 7539321821 in words is "seven billion, five hundred thirty-nine million, three hundred twenty-one thousand, eight hundred twenty-one".