9949989781 has 2 divisors, whose sum is σ = 9949989782. Its totient is φ = 9949989780.

The previous prime is 9949989737. The next prime is 9949989793. The reversal of 9949989781 is 1879899499.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8741315025 + 1208674756 = 93495^2 + 34766^2 .

It is a cyclic number.

It is not a de Polignac number, because 9949989781 - 2²¹ = 9947892629 is a prime.

It is a super-2 number, since 2×9949989781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9949989281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4974994890 + 4974994891.

It is an arithmetic number, because the mean of its divisors is an integer number (4974994891).

Almost surely, 2^9949989781 is an apocalyptic number.

It is an amenable number.

9949989781 is a deficient number, since it is larger than the sum of its proper divisors (1).

9949989781 is an equidigital number, since it uses as much as digits as its factorization.

9949989781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 105815808, while the sum is 73.

The square root of 9949989781 is about 99749.6354930683. The cubic root of 9949989781 is about 2150.8372279993.

The spelling of 9949989781 in words is "nine billion, nine hundred forty-nine million, nine hundred eighty-nine thousand, seven hundred eighty-one".