3931142909521 has 9 divisors (see below), whose sum is σ = 3937098062811. Its totient is φ = 3925196759232.

The previous prime is 3931142909513. The next prime is 3931142909527. The reversal of 3931142909521 is 1259092411393.

It is a happy number.

The square root of 3931142909521 is 1982711.

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

It can be written as a sum of positive squares in only one way, i.e., 3325024606225 + 606118303296 = 1823465^2 + 778536^2 .

It is not a de Polignac number, because 3931142909521 - 2³ = 3931142909513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3931142909527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1949003905 + ... + 1949005921.

Almost surely, 2^{3931142909521} is an apocalyptic number.

3931142909521 is the 1982711-st square number.

3931142909521 is the 991356-th centered octagonal number.

It is an amenable number.

3931142909521 is a deficient number, since it is larger than the sum of its proper divisors (5955153290).

3931142909521 is an frugal number, since it uses more digits than its factorization.

3931142909521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6000 (or 3000 counting only the distinct ones).

The product of its (nonzero) digits is 524880, while the sum is 49.

Multiplying 3931142909521 by its sum of digits (49), we get a square (192626002566529 = 13878977²).

The spelling of 3931142909521 in words is "three trillion, nine hundred thirty-one billion, one hundred forty-two million, nine hundred nine thousand, five hundred twenty-one".