9921457191 has 4 divisors (see below), whose sum is σ = 13228609592. Its totient is φ = 6614304792.

The previous prime is 9921457171. The next prime is 9921457199. The reversal of 9921457191 is 1917541299.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 9921457191 - 2⁶ = 9921457127 is a prime.

It is a super-2 number, since 2×9921457191² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9921457191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9921457199) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1653576196 + ... + 1653576201.

It is an arithmetic number, because the mean of its divisors is an integer number (3307152398).

Almost surely, 2^9921457191 is an apocalyptic number.

9921457191 is a deficient number, since it is larger than the sum of its proper divisors (3307152401).

9921457191 is a wasteful number, since it uses less digits than its factorization.

9921457191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3307152400.

The product of its digits is 204120, while the sum is 48.

The square root of 9921457191 is about 99606.5117901435. The cubic root of 9921457191 is about 2148.7793461219.

The spelling of 9921457191 in words is "nine billion, nine hundred twenty-one million, four hundred fifty-seven thousand, one hundred ninety-one".