721721907 has 12 divisors (see below), whose sum is σ = 1081098200. Its totient is φ = 481147776.

The previous prime is 721721863. The next prime is 721721909. The reversal of 721721907 is 709127127.

It is not a de Polignac number, because 721721907 - 2¹² = 721717811 is a prime.

It is a super-2 number, since 2×721721907² = 1041765022087433298, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721721909) 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 11 ways as a sum of consecutive naturals, for example, 1484782 + ... + 1485267.

Almost surely, 2^721721907 is an apocalyptic number.

721721907 is a deficient number, since it is larger than the sum of its proper divisors (359376293).

721721907 is an equidigital number, since it uses as much as digits as its factorization.

721721907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2970064 (or 2970052 counting only the distinct ones).

The product of its (nonzero) digits is 12348, while the sum is 36.

The square root of 721721907 is about 26864.8824118030. The cubic root of 721721907 is about 896.9948769855.

The spelling of 721721907 in words is "seven hundred twenty-one million, seven hundred twenty-one thousand, nine hundred seven".