13072721 has 4 divisors (see below), whose sum is σ = 13350912. Its totient is φ = 12794532.

The previous prime is 13072699. The next prime is 13072739. The reversal of 13072721 is 12727031.

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: 12727031 = 1319 ⋅9649.

It is a cyclic number.

It is not a de Polignac number, because 13072721 - 2²² = 8878417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (13072771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139025 + ... + 139118.

It is an arithmetic number, because the mean of its divisors is an integer number (3337728).

Almost surely, 2^13072721 is an apocalyptic number.

It is an amenable number.

13072721 is a deficient number, since it is larger than the sum of its proper divisors (278191).

13072721 is an equidigital number, since it uses as much as digits as its factorization.

13072721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278190.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 13072721 is about 3615.6217999122. The cubic root of 13072721 is about 235.5710932834.

Adding to 13072721 its reverse (12727031), we get a palindrome (25799752).

The spelling of 13072721 in words is "thirteen million, seventy-two thousand, seven hundred twenty-one".