11215721 has 8 divisors (see below), whose sum is σ = 12657600. Its totient is φ = 9844240.

The previous prime is 11215717. The next prime is 11215727. The reversal of 11215721 is 12751211.

It is a happy number.

11215721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 11215721 - 2² = 11215717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11215693 and 11215702.

It is not an unprimeable number, because it can be changed into a prime (11215727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17261 + ... + 17898.

It is an arithmetic number, because the mean of its divisors is an integer number (1582200).

Almost surely, 2^11215721 is an apocalyptic number.

11215721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11215721 is a deficient number, since it is larger than the sum of its proper divisors (1441879).

11215721 is a wasteful number, since it uses less digits than its factorization.

11215721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35199.

The product of its digits is 140, while the sum is 20.

The square root of 11215721 is about 3348.9880561149. The cubic root of 11215721 is about 223.8424234555.

Adding to 11215721 its reverse (12751211), we get a palindrome (23966932).

It can be divided in two parts, 11 and 215721, that multiplied together give a triangular number (2372931 = T₂₁₇₈).

The spelling of 11215721 in words is "eleven million, two hundred fifteen thousand, seven hundred twenty-one".