3991528215497 has 2 divisors, whose sum is σ = 3991528215498. Its totient is φ = 3991528215496.

The previous prime is 3991528215487. The next prime is 3991528215503. The reversal of 3991528215497 is 7945128251993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2147429398921 + 1844098816576 = 1465411^2 + 1357976^2 .

It is a cyclic number.

It is not a de Polignac number, because 3991528215497 - 2²² = 3991524021193 is a prime.

It is not a weakly prime, because it can be changed into another prime (3991528215487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1995764107748 + 1995764107749.

It is an arithmetic number, because the mean of its divisors is an integer number (1995764107749).

Almost surely, 2^{3991528215497} is an apocalyptic number.

It is an amenable number.

3991528215497 is a deficient number, since it is larger than the sum of its proper divisors (1).

3991528215497 is an equidigital number, since it uses as much as digits as its factorization.

3991528215497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48988800, while the sum is 65.

The spelling of 3991528215497 in words is "three trillion, nine hundred ninety-one billion, five hundred twenty-eight million, two hundred fifteen thousand, four hundred ninety-seven".