1921919186889 has 225 divisors, whose sum is σ = 3385681152249. Its totient is φ = 1085997818880.

The previous prime is 1921919186881. The next prime is 1921919186897. The reversal of 1921919186889 is 9886819191291.

The square root of 1921919186889 is 1386333.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (1921919186881) and next prime (1921919186897).

It can be written as a sum of positive squares in 22 ways, for example, as 1678566404025 + 243352782864 = 1295595^2 + 493308^2 .

It is not a de Polignac number, because 1921919186889 - 2³ = 1921919186881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1921919186881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 224 ways as a sum of consecutive naturals, for example, 46876077709 + ... + 46876077749.

Almost surely, 2^{1921919186889} is an apocalyptic number.

1921919186889 is the 1386333-rd square number.

1921919186889 is the 693167-th centered octagonal number.

It is an amenable number.

1921919186889 is a deficient number, since it is larger than the sum of its proper divisors (1463761965360).

1921919186889 is an frugal number, since it uses more digits than its factorization.

1921919186889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188 (or 74 counting only the distinct ones).

The product of its digits is 40310784, while the sum is 72.

The spelling of 1921919186889 in words is "one trillion, nine hundred twenty-one billion, nine hundred nineteen million, one hundred eighty-six thousand, eight hundred eighty-nine".