11391921 has 20 divisors (see below), whose sum is σ = 18020772. Its totient is φ = 7147008.

The previous prime is 11391899. The next prime is 11391931. The reversal of 11391921 is 12919311.

It can be written as a sum of positive squares in 2 ways, for example, as 8767521 + 2624400 = 2961^2 + 1620^2 .

It is not a de Polignac number, because 11391921 - 2⁶ = 11391857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (11391931) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2760 + ... + 5513.

Almost surely, 2^11391921 is an apocalyptic number.

It is an amenable number.

11391921 is a deficient number, since it is larger than the sum of its proper divisors (6628851).

11391921 is an equidigital number, since it uses as much as digits as its factorization.

11391921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8302 (or 8293 counting only the distinct ones).

The product of its digits is 486, while the sum is 27.

The square root of 11391921 is about 3375.1919945390. The cubic root of 11391921 is about 225.0085330097.

The spelling of 11391921 in words is "eleven million, three hundred ninety-one thousand, nine hundred twenty-one".