1991822563642 has 8 divisors (see below), whose sum is σ = 2988170605332. Its totient is φ = 995765695200.

The previous prime is 1991822563501. The next prime is 1991822563649. The reversal of 1991822563642 is 2463652281991.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1916981471601 + 74841092041 = 1384551^2 + 273571^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (1991822563649) 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, 72776209 + ... + 72803572.

Almost surely, 2^{1991822563642} is an apocalyptic number.

1991822563642 is a deficient number, since it is larger than the sum of its proper divisors (996348041690).

1991822563642 is a wasteful number, since it uses less digits than its factorization.

1991822563642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145586624.

The product of its digits is 11197440, while the sum is 58.

The spelling of 1991822563642 in words is "one trillion, nine hundred ninety-one billion, eight hundred twenty-two million, five hundred sixty-three thousand, six hundred forty-two".