1371889991 has 2 divisors, whose sum is σ = 1371889992. Its totient is φ = 1371889990.

The previous prime is 1371889957. The next prime is 1371889997. The reversal of 1371889991 is 1999881731.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1371889991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1371889997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 685944995 + 685944996.

It is an arithmetic number, because the mean of its divisors is an integer number (685944996).

Almost surely, 2^1371889991 is an apocalyptic number.

1371889991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1371889991 is an equidigital number, since it uses as much as digits as its factorization.

1371889991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 979776, while the sum is 56.

The square root of 1371889991 is about 37039.0333432178. The cubic root of 1371889991 is about 1111.1510368761.

The spelling of 1371889991 in words is "one billion, three hundred seventy-one million, eight hundred eighty-nine thousand, nine hundred ninety-one".