971913991 has 2 divisors, whose sum is σ = 971913992. Its totient is φ = 971913990.

The previous prime is 971913983. The next prime is 971914001. The reversal of 971913991 is 199319179.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 971913991 - 2³ = 971913983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (971913961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 485956995 + 485956996.

It is an arithmetic number, because the mean of its divisors is an integer number (485956996).

Almost surely, 2^971913991 is an apocalyptic number.

971913991 is a deficient number, since it is larger than the sum of its proper divisors (1).

971913991 is an equidigital number, since it uses as much as digits as its factorization.

971913991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 137781, while the sum is 49.

The square root of 971913991 is about 31175.5351357439. The cubic root of 971913991 is about 990.5489561666.

The spelling of 971913991 in words is "nine hundred seventy-one million, nine hundred thirteen thousand, nine hundred ninety-one".