997891387 has 2 divisors, whose sum is σ = 997891388. Its totient is φ = 997891386.

The previous prime is 997891337. The next prime is 997891393. The reversal of 997891387 is 783198799.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 997891387 - 2²³ = 989502779 is a prime.

It is not a weakly prime, because it can be changed into another prime (997891337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498945693 + 498945694.

It is an arithmetic number, because the mean of its divisors is an integer number (498945694).

Almost surely, 2^997891387 is an apocalyptic number.

997891387 is a deficient number, since it is larger than the sum of its proper divisors (1).

997891387 is an equidigital number, since it uses as much as digits as its factorization.

997891387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6858432, while the sum is 61.

The square root of 997891387 is about 31589.4189088688. The cubic root of 997891387 is about 999.2966343928.

The spelling of 997891387 in words is "nine hundred ninety-seven million, eight hundred ninety-one thousand, three hundred eighty-seven".