9921621869 has 2 divisors, whose sum is σ = 9921621870. Its totient is φ = 9921621868.

The previous prime is 9921621841. The next prime is 9921621883. The reversal of 9921621869 is 9681261299.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9912591844 + 9030025 = 99562^2 + 3005^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9921621869 is a prime.

It is a super-2 number, since 2×9921621869² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 9921621869.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9921629869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4960810934 + 4960810935.

It is an arithmetic number, because the mean of its divisors is an integer number (4960810935).

Almost surely, 2^9921621869 is an apocalyptic number.

It is an amenable number.

9921621869 is a deficient number, since it is larger than the sum of its proper divisors (1).

9921621869 is an equidigital number, since it uses as much as digits as its factorization.

9921621869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 839808, while the sum is 53.

The square root of 9921621869 is about 99607.3384294551. The cubic root of 9921621869 is about 2148.7912346553.

The spelling of 9921621869 in words is "nine billion, nine hundred twenty-one million, six hundred twenty-one thousand, eight hundred sixty-nine".