721512101 has 2 divisors, whose sum is σ = 721512102. Its totient is φ = 721512100.

The previous prime is 721512089. The next prime is 721512131. The reversal of 721512101 is 101215127.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 484044001 + 237468100 = 22001^2 + 15410^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721512101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721512131) 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 as a sum of consecutive naturals, namely, 360756050 + 360756051.

It is an arithmetic number, because the mean of its divisors is an integer number (360756051).

Almost surely, 2^721512101 is an apocalyptic number.

It is an amenable number.

721512101 is a deficient number, since it is larger than the sum of its proper divisors (1).

721512101 is an equidigital number, since it uses as much as digits as its factorization.

721512101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 140, while the sum is 20.

The square root of 721512101 is about 26860.9772904859. The cubic root of 721512101 is about 896.9079491608.

Adding to 721512101 its reverse (101215127), we get a palindrome (822727228).

The spelling of 721512101 in words is "seven hundred twenty-one million, five hundred twelve thousand, one hundred one".