1911890681 has 2 divisors, whose sum is σ = 1911890682. Its totient is φ = 1911890680.

The previous prime is 1911890671. The next prime is 1911890719. The reversal of 1911890681 is 1860981191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1856834281 + 55056400 = 43091^2 + 7420^2 .

It is an emirp because it is prime and its reverse (1860981191) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1890681161 and 1611860981.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1911890681 is a prime.

It is a super-2 number, since 2×1911890681² = 7310651952189287522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1911890611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 955945340 + 955945341.

It is an arithmetic number, because the mean of its divisors is an integer number (955945341).

Almost surely, 2^1911890681 is an apocalyptic number.

It is an amenable number.

1911890681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1911890681 is an equidigital number, since it uses as much as digits as its factorization.

1911890681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 44.

The square root of 1911890681 is about 43725.1721666136. The cubic root of 1911890681 is about 1241.1407039177.

The spelling of 1911890681 in words is "one billion, nine hundred eleven million, eight hundred ninety thousand, six hundred eighty-one".