1001391 has 8 divisors (see below), whose sum is σ = 1339824. Its totient is φ = 665280.

The previous prime is 1001389. The next prime is 1001401. The reversal of 1001391 is 1931001.

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

It is not a de Polignac number, because 1001391 - 2¹ = 1001389 is a prime.

1001391 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1001391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001311) 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, 1315 + ... + 1931.

It is an arithmetic number, because the mean of its divisors is an integer number (167478).

2^1001391 is an apocalyptic number.

1001391 is a deficient number, since it is larger than the sum of its proper divisors (338433).

1001391 is an equidigital number, since it uses as much as digits as its factorization.

1001391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1161.

The product of its (nonzero) digits is 27, while the sum is 15.

The square root of 1001391 is about 1000.6952583079. The cubic root of 1001391 is about 100.0463451846.

Adding to 1001391 its reverse (1931001), we get a palindrome (2932392).

The spelling of 1001391 in words is "one million, one thousand, three hundred ninety-one".