13213721 has 8 divisors (see below), whose sum is σ = 14206080. Its totient is φ = 12251088.

The previous prime is 13213703. The next prime is 13213747. The reversal of 13213721 is 12731231.

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 13213721 - 2¹⁰ = 13212697 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13213693 and 13213702.

It is not an unprimeable number, because it can be changed into a prime (13213121) 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, 6506 + ... + 8291.

It is an arithmetic number, because the mean of its divisors is an integer number (1775760).

Almost surely, 2^13213721 is an apocalyptic number.

It is an amenable number.

13213721 is a deficient number, since it is larger than the sum of its proper divisors (992359).

13213721 is a wasteful number, since it uses less digits than its factorization.

13213721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14863.

The product of its digits is 252, while the sum is 20.

The square root of 13213721 is about 3635.0682249443. The cubic root of 13213721 is about 236.4150087861.

Adding to 13213721 its reverse (12731231), we get a palindrome (25944952).

The spelling of 13213721 in words is "thirteen million, two hundred thirteen thousand, seven hundred twenty-one".