9921911609 has 2 divisors, whose sum is σ = 9921911610. Its totient is φ = 9921911608.

The previous prime is 9921911599. The next prime is 9921911621. The reversal of 9921911609 is 9061191299.

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., 7961635984 + 1960275625 = 89228^2 + 44275^2 .

It is an emirp because it is prime and its reverse (9061191299) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9921911609 - 2²⁸ = 9653476153 is a prime.

It is not a weakly prime, because it can be changed into another prime (9921911669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4960955804 + 4960955805.

It is an arithmetic number, because the mean of its divisors is an integer number (4960955805).

Almost surely, 2^9921911609 is an apocalyptic number.

It is an amenable number.

9921911609 is a deficient number, since it is larger than the sum of its proper divisors (1).

9921911609 is an equidigital number, since it uses as much as digits as its factorization.

9921911609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 78732, while the sum is 47.

The square root of 9921911609 is about 99608.7928297497. The cubic root of 9921911609 is about 2148.8121514208.

The spelling of 9921911609 in words is "nine billion, nine hundred twenty-one million, nine hundred eleven thousand, six hundred nine".