3991389197 has 2 divisors, whose sum is σ = 3991389198. Its totient is φ = 3991389196.

The previous prime is 3991389107. The next prime is 3991389209. The reversal of 3991389197 is 7919831993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3645019876 + 346369321 = 60374^2 + 18611^2 .

It is a cyclic number.

It is not a de Polignac number, because 3991389197 - 2²⁴ = 3974611981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3991389107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1995694598 + 1995694599.

It is an arithmetic number, because the mean of its divisors is an integer number (1995694599).

Almost surely, 2^3991389197 is an apocalyptic number.

It is an amenable number.

3991389197 is a deficient number, since it is larger than the sum of its proper divisors (1).

3991389197 is an equidigital number, since it uses as much as digits as its factorization.

3991389197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3306744, while the sum is 59.

The square root of 3991389197 is about 63177.4421530343. The cubic root of 3991389197 is about 1586.2611671545.

The spelling of 3991389197 in words is "three billion, nine hundred ninety-one million, three hundred eighty-nine thousand, one hundred ninety-seven".