11951821 has 4 divisors (see below), whose sum is σ = 13659232. Its totient is φ = 10244412.

The previous prime is 11951813. The next prime is 11951827. The reversal of 11951821 is 12815911.

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: 12815911 = 89 ⋅143999.

It is a cyclic number.

It is not a de Polignac number, because 11951821 - 2³ = 11951813 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 11951821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11951827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 853695 + ... + 853708.

It is an arithmetic number, because the mean of its divisors is an integer number (3414808).

Almost surely, 2^11951821 is an apocalyptic number.

It is an amenable number.

11951821 is a deficient number, since it is larger than the sum of its proper divisors (1707411).

11951821 is an equidigital number, since it uses as much as digits as its factorization.

11951821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1707410.

The product of its digits is 720, while the sum is 28.

The square root of 11951821 is about 3457.1405814632. The cubic root of 11951821 is about 228.6360420567.

The spelling of 11951821 in words is "eleven million, nine hundred fifty-one thousand, eight hundred twenty-one".