1306680721 has 4 divisors (see below), whose sum is σ = 1348831744. Its totient is φ = 1264529700.

The previous prime is 1306680691. The next prime is 1306680737. The reversal of 1306680721 is 1270866031.

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.

It is a cyclic number.

It is not a de Polignac number, because 1306680721 - 2¹¹ = 1306678673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1306680751) 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, 21075465 + ... + 21075526.

It is an arithmetic number, because the mean of its divisors is an integer number (337207936).

Almost surely, 2^1306680721 is an apocalyptic number.

It is an amenable number.

1306680721 is a deficient number, since it is larger than the sum of its proper divisors (42151023).

1306680721 is an equidigital number, since it uses as much as digits as its factorization.

1306680721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42151022.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 1306680721 is about 36148.0389647903. The cubic root of 1306680721 is about 1093.2592514891.

The spelling of 1306680721 in words is "one billion, three hundred six million, six hundred eighty thousand, seven hundred twenty-one".