351000721 has 2 divisors, whose sum is σ = 351000722. Its totient is φ = 351000720.

The previous prime is 351000719. The next prime is 351000731. The reversal of 351000721 is 127000153.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 239909121 + 111091600 = 15489^2 + 10540^2 .

It is a cyclic number.

It is not a de Polignac number, because 351000721 - 2¹ = 351000719 is a prime.

It is a super-4 number, since 4×351000721⁴ (a number of 35 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

Together with 351000719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (351000731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 175500360 + 175500361.

It is an arithmetic number, because the mean of its divisors is an integer number (175500361).

Almost surely, 2^351000721 is an apocalyptic number.

It is an amenable number.

351000721 is a deficient number, since it is larger than the sum of its proper divisors (1).

351000721 is an equidigital number, since it uses as much as digits as its factorization.

351000721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 351000721 is about 18735.0132372518. The cubic root of 351000721 is about 705.4008893109.

Adding to 351000721 its reverse (127000153), we get a palindrome (478000874).

The spelling of 351000721 in words is "three hundred fifty-one million, seven hundred twenty-one", and thus it is an aban number.