9919681 has 2 divisors, whose sum is σ = 9919682. Its totient is φ = 9919680.

The previous prime is 9919669. The next prime is 9919697. The reversal of 9919681 is 1869199.

9919681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9000000 + 919681 = 3000^2 + 959^2 .

It is an emirp because it is prime and its reverse (1869199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9919681 is a prime.

It is a super-2 number, since 2×9919681² = 196800142283522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (9916681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4959840 + 4959841.

It is an arithmetic number, because the mean of its divisors is an integer number (4959841).

Almost surely, 2^9919681 is an apocalyptic number.

It is an amenable number.

9919681 is a deficient number, since it is larger than the sum of its proper divisors (1).

9919681 is an equidigital number, since it uses as much as digits as its factorization.

9919681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 43.

The square root of 9919681 is about 3149.5525078970. The cubic root of 9919681 is about 214.8651109908.

It can be divided in two parts, 9 and 919681, that multiplied together give a square (8277129 = 2877²).

The spelling of 9919681 in words is "nine million, nine hundred nineteen thousand, six hundred eighty-one".