891619691 has 2 divisors, whose sum is σ = 891619692. Its totient is φ = 891619690.

The previous prime is 891619649. The next prime is 891619693. The reversal of 891619691 is 196916198.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 891619691 - 2⁶ = 891619627 is a prime.

Together with 891619693, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (891619693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445809845 + 445809846.

It is an arithmetic number, because the mean of its divisors is an integer number (445809846).

Almost surely, 2^891619691 is an apocalyptic number.

891619691 is a deficient number, since it is larger than the sum of its proper divisors (1).

891619691 is an equidigital number, since it uses as much as digits as its factorization.

891619691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 50.

The square root of 891619691 is about 29860.0015237776. The cubic root of 891619691 is about 962.4833314930.

The spelling of 891619691 in words is "eight hundred ninety-one million, six hundred nineteen thousand, six hundred ninety-one".