971188721 has 4 divisors (see below), whose sum is σ = 971274612. Its totient is φ = 971102832.

The previous prime is 971188711. The next prime is 971188759. The reversal of 971188721 is 127881179.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 298045696 + 673143025 = 17264^2 + 25945^2 .

It is a cyclic number.

It is not a de Polignac number, because 971188721 - 2¹⁰ = 971187697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (971188711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22850 + ... + 49643.

It is an arithmetic number, because the mean of its divisors is an integer number (242818653).

Almost surely, 2^971188721 is an apocalyptic number.

It is an amenable number.

971188721 is a deficient number, since it is larger than the sum of its proper divisors (85891).

971188721 is a wasteful number, since it uses less digits than its factorization.

971188721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85890.

The product of its digits is 56448, while the sum is 44.

The square root of 971188721 is about 31163.9009271946. The cubic root of 971188721 is about 990.3025028717.

The spelling of 971188721 in words is "nine hundred seventy-one million, one hundred eighty-eight thousand, seven hundred twenty-one".