9990437381 has 2 divisors, whose sum is σ = 9990437382. Its totient is φ = 9990437380.

The previous prime is 9990437371. The next prime is 9990437467. The reversal of 9990437381 is 1837340999.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8680648900 + 1309788481 = 93170^2 + 36191^2 .

It is a cyclic number.

It is not a de Polignac number, because 9990437381 - 2²² = 9986243077 is a prime.

It is a super-2 number, since 2×9990437381² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9990437351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995218690 + 4995218691.

It is an arithmetic number, because the mean of its divisors is an integer number (4995218691).

Almost surely, 2^9990437381 is an apocalyptic number.

It is an amenable number.

9990437381 is a deficient number, since it is larger than the sum of its proper divisors (1).

9990437381 is an equidigital number, since it uses as much as digits as its factorization.

9990437381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1469664, while the sum is 53.

The square root of 9990437381 is about 99952.1754690712. The cubic root of 9990437381 is about 2153.7477364128.

The spelling of 9990437381 in words is "nine billion, nine hundred ninety million, four hundred thirty-seven thousand, three hundred eighty-one".