1921521866769 has 16 divisors (see below), whose sum is σ = 2885694942400. Its totient is φ = 1263466431648.

The previous prime is 1921521866767. The next prime is 1921521866783. The reversal of 1921521866769 is 9676681251291.

1921521866769 is a `hidden beast` number, since 1 + 9 + 21 + 521 + 86 + 6 + 7 + 6 + 9 = 666.

It is not a de Polignac number, because 1921521866769 - 2¹ = 1921521866767 is a prime.

It is a super-2 number, since 2×1921521866769² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1921521866767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 487446499 + ... + 487450440.

It is an arithmetic number, because the mean of its divisors is an integer number (180355933900).

Almost surely, 2^{1921521866769} is an apocalyptic number.

It is an amenable number.

1921521866769 is a deficient number, since it is larger than the sum of its proper divisors (964173075631).

1921521866769 is an equidigital number, since it uses as much as digits as its factorization.

1921521866769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 974897021 (or 974897015 counting only the distinct ones).

The product of its digits is 19595520, while the sum is 63.

The spelling of 1921521866769 in words is "one trillion, nine hundred twenty-one billion, five hundred twenty-one million, eight hundred sixty-six thousand, seven hundred sixty-nine".