3957689521 has 4 divisors (see below), whose sum is σ = 3962276352. Its totient is φ = 3953102692.

The previous prime is 3957689503. The next prime is 3957689591. The reversal of 3957689521 is 1259867593.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1259867593 = 9643 ⋅130651.

It is a cyclic number.

It is not a de Polignac number, because 3957689521 - 2¹¹ = 3957687473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3957689591) 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, 2292121 + ... + 2293846.

It is an arithmetic number, because the mean of its divisors is an integer number (990569088).

Almost surely, 2^3957689521 is an apocalyptic number.

It is an amenable number.

3957689521 is a deficient number, since it is larger than the sum of its proper divisors (4586831).

3957689521 is an equidigital number, since it uses as much as digits as its factorization.

3957689521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4586830.

The product of its digits is 4082400, while the sum is 55.

The square root of 3957689521 is about 62910.1702509221. The cubic root of 3957689521 is about 1581.7842260465.

The spelling of 3957689521 in words is "three billion, nine hundred fifty-seven million, six hundred eighty-nine thousand, five hundred twenty-one".