1991442321 has 48 divisors (see below), whose sum is σ = 3253286400. Its totient is φ = 1203063840.

The previous prime is 1991442319. The next prime is 1991442331. The reversal of 1991442321 is 1232441991.

1991442321 is a `hidden beast` number, since 199 + 1 + 442 + 3 + 21 = 666.

It is not a de Polignac number, because 1991442321 - 2¹ = 1991442319 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1991442331) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1270080 + ... + 1271646.

It is an arithmetic number, because the mean of its divisors is an integer number (67776800).

Almost surely, 2^1991442321 is an apocalyptic number.

1991442321 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1991442321 is a deficient number, since it is larger than the sum of its proper divisors (1261844079).

1991442321 is a wasteful number, since it uses less digits than its factorization.

1991442321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1987 (or 1970 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 1991442321 is about 44625.5792231317. The cubic root of 1991442321 is about 1258.1214807749.

The spelling of 1991442321 in words is "one billion, nine hundred ninety-one million, four hundred forty-two thousand, three hundred twenty-one".