11721621 has 4 divisors (see below), whose sum is σ = 15628832. Its totient is φ = 7814412.

The previous prime is 11721607. The next prime is 11721623. The reversal of 11721621 is 12612711.

It is a happy number.

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: 12612711 = 3 ⋅4204237.

It is not a de Polignac number, because 11721621 - 2¹⁴ = 11705237 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11721623) 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, 1953601 + ... + 1953606.

It is an arithmetic number, because the mean of its divisors is an integer number (3907208).

Almost surely, 2^11721621 is an apocalyptic number.

It is an amenable number.

11721621 is a deficient number, since it is larger than the sum of its proper divisors (3907211).

11721621 is an equidigital number, since it uses as much as digits as its factorization.

11721621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3907210.

The product of its digits is 168, while the sum is 21.

The square root of 11721621 is about 3423.6852951169. The cubic root of 11721621 is about 227.1586217564.

The spelling of 11721621 in words is "eleven million, seven hundred twenty-one thousand, six hundred twenty-one".