7971009521 has 4 divisors (see below), whose sum is σ = 8439892452. Its totient is φ = 7502126592.

The previous prime is 7971009461. The next prime is 7971009539. The reversal of 7971009521 is 1259001797.

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 7412349025 + 558660496 = 86095^2 + 23636^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7971009521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7971009121) 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, 234441440 + ... + 234441473.

It is an arithmetic number, because the mean of its divisors is an integer number (2109973113).

Almost surely, 2^7971009521 is an apocalyptic number.

It is an amenable number.

7971009521 is a deficient number, since it is larger than the sum of its proper divisors (468882931).

7971009521 is a wasteful number, since it uses less digits than its factorization.

7971009521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468882930.

The product of its (nonzero) digits is 39690, while the sum is 41.

The square root of 7971009521 is about 89280.5103088014. The cubic root of 7971009521 is about 1997.5812026389.

The spelling of 7971009521 in words is "seven billion, nine hundred seventy-one million, nine thousand, five hundred twenty-one".