1691228389091 has 4 divisors (see below), whose sum is σ = 1693025657184. Its totient is φ = 1689431121000.

The previous prime is 1691228389073. The next prime is 1691228389133. The reversal of 1691228389091 is 1909838221961.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1691228389091 - 2³⁰ = 1690154647267 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1691228389091.

It is not an unprimeable number, because it can be changed into a prime (1691228389051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 898632635 + ... + 898634516.

It is an arithmetic number, because the mean of its divisors is an integer number (423256414296).

Almost surely, 2^{1691228389091} is an apocalyptic number.

1691228389091 is a deficient number, since it is larger than the sum of its proper divisors (1797268093).

1691228389091 is an equidigital number, since it uses as much as digits as its factorization.

1691228389091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1797268092.

The product of its (nonzero) digits is 3359232, while the sum is 59.

The spelling of 1691228389091 in words is "one trillion, six hundred ninety-one billion, two hundred twenty-eight million, three hundred eighty-nine thousand, ninety-one".