9181991901 has 4 divisors (see below), whose sum is σ = 12242655872. Its totient is φ = 6121327932.

The previous prime is 9181991881. The next prime is 9181991909. The reversal of 9181991901 is 1091991819.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 9181991901 - 2²¹ = 9179894749 is a prime.

It is a super-3 number, since 3×9181991901³ (a number of 31 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9181991909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1530331981 + ... + 1530331986.

It is an arithmetic number, because the mean of its divisors is an integer number (3060663968).

Almost surely, 2^9181991901 is an apocalyptic number.

It is an amenable number.

9181991901 is a deficient number, since it is larger than the sum of its proper divisors (3060663971).

9181991901 is a wasteful number, since it uses less digits than its factorization.

9181991901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3060663970.

The product of its (nonzero) digits is 52488, while the sum is 48.

The square root of 9181991901 is about 95822.7107788128. The cubic root of 9181991901 is about 2094.0110468771.

The spelling of 9181991901 in words is "nine billion, one hundred eighty-one million, nine hundred ninety-one thousand, nine hundred one".