721101649 has 2 divisors, whose sum is σ = 721101650. Its totient is φ = 721101648.

The previous prime is 721101613. The next prime is 721101653. The reversal of 721101649 is 946101127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 478209424 + 242892225 = 21868^2 + 15585^2 .

It is a cyclic number.

It is not a de Polignac number, because 721101649 - 2²¹ = 719004497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721101649.

It is not a weakly prime, because it can be changed into another prime (721101659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360550824 + 360550825.

It is an arithmetic number, because the mean of its divisors is an integer number (360550825).

Almost surely, 2^721101649 is an apocalyptic number.

It is an amenable number.

721101649 is a deficient number, since it is larger than the sum of its proper divisors (1).

721101649 is an equidigital number, since it uses as much as digits as its factorization.

721101649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 721101649 is about 26853.3359007778. The cubic root of 721101649 is about 896.7378399824.

The spelling of 721101649 in words is "seven hundred twenty-one million, one hundred one thousand, six hundred forty-nine".