1891284991 has 2 divisors, whose sum is σ = 1891284992. Its totient is φ = 1891284990.

The previous prime is 1891284979. The next prime is 1891285001. The reversal of 1891284991 is 1994821981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1891284991 - 2²⁵ = 1857730559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1891284971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 945642495 + 945642496.

It is an arithmetic number, because the mean of its divisors is an integer number (945642496).

Almost surely, 2^1891284991 is an apocalyptic number.

1891284991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1891284991 is an equidigital number, since it uses as much as digits as its factorization.

1891284991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 52.

The square root of 1891284991 is about 43488.9065279871. The cubic root of 1891284991 is about 1236.6657282908.

The spelling of 1891284991 in words is "one billion, eight hundred ninety-one million, two hundred eighty-four thousand, nine hundred ninety-one".