9131904721 has 3 divisors (see below), whose sum is σ = 9132000283. Its totient is φ = 9131809160.

The previous prime is 9131904713. The next prime is 9131904757. The reversal of 9131904721 is 1274091319.

The square root of 9131904721 is 95561.

It is a perfect power (a square), and thus also a powerful number.

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 only one way, i.e., 3750215121 + 5381689600 = 61239^2 + 73360^2 .

It is not a de Polignac number, because 9131904721 - 2³ = 9131904713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9131904421) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 47781 + ... + 143341.

Almost surely, 2^9131904721 is an apocalyptic number.

9131904721 is the 95561-st square number.

9131904721 is the 47781-st centered octagonal number.

It is an amenable number.

9131904721 is a deficient number, since it is larger than the sum of its proper divisors (95562).

9131904721 is an frugal number, since it uses more digits than its factorization.

9131904721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191122 (or 95561 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 37.

The cubic root of 9131904721 is about 2090.1965369232.

The spelling of 9131904721 in words is "nine billion, one hundred thirty-one million, nine hundred four thousand, seven hundred twenty-one".