12920721 has 8 divisors (see below), whose sum is σ = 18793824. Its totient is φ = 7830720.

The previous prime is 12920717. The next prime is 12920737. The reversal of 12920721 is 12702921.

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

It is not a de Polignac number, because 12920721 - 2² = 12920717 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 12920691 and 12920700.

It is not an unprimeable number, because it can be changed into a prime (12920821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 195736 + ... + 195801.

It is an arithmetic number, because the mean of its divisors is an integer number (2349228).

Almost surely, 2^12920721 is an apocalyptic number.

12920721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12920721 is a deficient number, since it is larger than the sum of its proper divisors (5873103).

12920721 is a wasteful number, since it uses less digits than its factorization.

12920721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391551.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 12920721 is about 3594.5404435060. The cubic root of 12920721 is about 234.6545157258.

The spelling of 12920721 in words is "twelve million, nine hundred twenty thousand, seven hundred twenty-one".