919978691 has 2 divisors, whose sum is σ = 919978692. Its totient is φ = 919978690.

The previous prime is 919978673. The next prime is 919978739. The reversal of 919978691 is 196879919.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 919978691 - 2⁶ = 919978627 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 919978691.

It is not a weakly prime, because it can be changed into another prime (919978291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 459989345 + 459989346.

It is an arithmetic number, because the mean of its divisors is an integer number (459989346).

Almost surely, 2^919978691 is an apocalyptic number.

919978691 is a deficient number, since it is larger than the sum of its proper divisors (1).

919978691 is an equidigital number, since it uses as much as digits as its factorization.

919978691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2204496, while the sum is 59.

The square root of 919978691 is about 30331.1505057095. The cubic root of 919978691 is about 972.5813171408.

The spelling of 919978691 in words is "nine hundred nineteen million, nine hundred seventy-eight thousand, six hundred ninety-one".