991081091001 has 8 divisors (see below), whose sum is σ = 1322465039584. Its totient is φ = 660208934880.

The previous prime is 991081090999. The next prime is 991081091023. The reversal of 991081091001 is 100190180199.

991081091001 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 991081091001 - 2¹ = 991081090999 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (991081091051) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127943596 + ... + 127951341.

It is an arithmetic number, because the mean of its divisors is an integer number (165308129948).

Almost surely, 2^991081091001 is an apocalyptic number.

It is an amenable number.

991081091001 is a deficient number, since it is larger than the sum of its proper divisors (331383948583).

991081091001 is a wasteful number, since it uses less digits than its factorization.

991081091001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255896231.

The product of its (nonzero) digits is 5832, while the sum is 39.

The spelling of 991081091001 in words is "nine hundred ninety-one billion, eighty-one million, ninety-one thousand, one".