9901621591 has 2 divisors, whose sum is σ = 9901621592. Its totient is φ = 9901621590.

The previous prime is 9901621519. The next prime is 9901621607. The reversal of 9901621591 is 1951261099.

9901621591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with previous prime (9901621519) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 9901621591 - 2²³ = 9893232983 is a prime.

It is a super-2 number, since 2×9901621591² (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 (9901621091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4950810795 + 4950810796.

It is an arithmetic number, because the mean of its divisors is an integer number (4950810796).

Almost surely, 2^9901621591 is an apocalyptic number.

9901621591 is a deficient number, since it is larger than the sum of its proper divisors (1).

9901621591 is an equidigital number, since it uses as much as digits as its factorization.

9901621591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43740, while the sum is 43.

The square root of 9901621591 is about 99506.8921783813. The cubic root of 9901621591 is about 2147.3463992345.

The spelling of 9901621591 in words is "nine billion, nine hundred one million, six hundred twenty-one thousand, five hundred ninety-one".