9901621091 has 2 divisors, whose sum is σ = 9901621092. Its totient is φ = 9901621090.

The previous prime is 9901621039. The next prime is 9901621181. The reversal of 9901621091 is 1901261099.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9901621091 - 2¹⁴ = 9901604707 is a prime.

It is not a weakly prime, because it can be changed into another prime (9901621291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4950810545 + 4950810546.

It is an arithmetic number, because the mean of its divisors is an integer number (4950810546).

Almost surely, 2^9901621091 is an apocalyptic number.

9901621091 is a deficient number, since it is larger than the sum of its proper divisors (1).

9901621091 is an equidigital number, since it uses as much as digits as its factorization.

9901621091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8748, while the sum is 38.

The square root of 9901621091 is about 99506.8896659925. The cubic root of 9901621091 is about 2147.3463630898.

The spelling of 9901621091 in words is "nine billion, nine hundred one million, six hundred twenty-one thousand, ninety-one".