1991880064969 has 8 divisors (see below), whose sum is σ = 2041207043400. Its totient is φ = 1942588540800.

The previous prime is 1991880064963. The next prime is 1991880064991. The reversal of 1991880064969 is 9694600881991.

It can be written as a sum of positive squares in 4 ways, for example, as 155074502025 + 1836805562944 = 393795^2 + 1355288^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1991880064969 - 2⁷ = 1991880064841 is a prime.

It is a super-2 number, since 2×1991880064969² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1991880064898 and 1991880064907.

It is not an unprimeable number, because it can be changed into a prime (1991880064963) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8749794 + ... + 8974555.

It is an arithmetic number, because the mean of its divisors is an integer number (255150880425).

Almost surely, 2^{1991880064969} is an apocalyptic number.

It is an amenable number.

1991880064969 is a deficient number, since it is larger than the sum of its proper divisors (49326978431).

1991880064969 is a wasteful number, since it uses less digits than its factorization.

1991880064969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17727131.

The product of its (nonzero) digits is 60466176, while the sum is 70.

The spelling of 1991880064969 in words is "one trillion, nine hundred ninety-one billion, eight hundred eighty million, sixty-four thousand, nine hundred sixty-nine".