891997243 has 2 divisors, whose sum is σ = 891997244. Its totient is φ = 891997242.

The previous prime is 891997241. The next prime is 891997277. The reversal of 891997243 is 342799198.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 891997243 - 2¹ = 891997241 is a prime.

Together with 891997241, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (891997241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445998621 + 445998622.

It is an arithmetic number, because the mean of its divisors is an integer number (445998622).

Almost surely, 2^891997243 is an apocalyptic number.

891997243 is a deficient number, since it is larger than the sum of its proper divisors (1).

891997243 is an equidigital number, since it uses as much as digits as its factorization.

891997243 is an evil number, because the sum of its binary digits is even.

The product of its digits is 979776, while the sum is 52.

The square root of 891997243 is about 29866.3228905066. The cubic root of 891997243 is about 962.6191652761.

The spelling of 891997243 in words is "eight hundred ninety-one million, nine hundred ninety-seven thousand, two hundred forty-three".