11867821 has 4 divisors (see below), whose sum is σ = 13563232. Its totient is φ = 10172412.

The previous prime is 11867809. The next prime is 11867827. The reversal of 11867821 is 12876811.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12876811 = 31 ⋅415381.

It is a cyclic number.

It is not a de Polignac number, because 11867821 - 2⁷ = 11867693 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 (11867827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 847695 + ... + 847708.

It is an arithmetic number, because the mean of its divisors is an integer number (3390808).

Almost surely, 2^11867821 is an apocalyptic number.

It is an amenable number.

11867821 is a deficient number, since it is larger than the sum of its proper divisors (1695411).

11867821 is an equidigital number, since it uses as much as digits as its factorization.

11867821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1695410.

The product of its digits is 5376, while the sum is 34.

The square root of 11867821 is about 3444.9703917450. The cubic root of 11867821 is about 228.0991476552.

The spelling of 11867821 in words is "eleven million, eight hundred sixty-seven thousand, eight hundred twenty-one".