11721439 has 4 divisors (see below), whose sum is σ = 11733840. Its totient is φ = 11709040.

The previous prime is 11721431. The next prime is 11721443. The reversal of 11721439 is 93412711.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93412711 = 7 ⋅13344673.

It is a cyclic number.

It is not a de Polignac number, because 11721439 - 2³ = 11721431 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 (11721431) 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, 4654 + ... + 6715.

It is an arithmetic number, because the mean of its divisors is an integer number (2933460).

Almost surely, 2^11721439 is an apocalyptic number.

11721439 is a deficient number, since it is larger than the sum of its proper divisors (12401).

11721439 is a wasteful number, since it uses less digits than its factorization.

11721439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12400.

The product of its digits is 1512, while the sum is 28.

The square root of 11721439 is about 3423.6587154680. The cubic root of 11721439 is about 227.1574460634.

It can be divided in two parts, 1 and 1721439, that added together give a triangular number (1721440 = T₁₈₅₅).

The spelling of 11721439 in words is "eleven million, seven hundred twenty-one thousand, four hundred thirty-nine".