9919781391 has 8 divisors (see below), whose sum is σ = 14243788720. Its totient is φ = 6104480832.

The previous prime is 9919781381. The next prime is 9919781393. The reversal of 9919781391 is 1931879199.

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

It is not a de Polignac number, because 9919781391 - 2¹¹ = 9919779343 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9919781393) 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, 127176646 + ... + 127176723.

It is an arithmetic number, because the mean of its divisors is an integer number (1780473590).

Almost surely, 2^9919781391 is an apocalyptic number.

9919781391 is a deficient number, since it is larger than the sum of its proper divisors (4324007329).

9919781391 is a wasteful number, since it uses less digits than its factorization.

9919781391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254353385.

The product of its digits is 1102248, while the sum is 57.

The square root of 9919781391 is about 99598.0993342744. The cubic root of 9919781391 is about 2148.6583582765.

The spelling of 9919781391 in words is "nine billion, nine hundred nineteen million, seven hundred eighty-one thousand, three hundred ninety-one".