721385101 has 4 divisors (see below), whose sum is σ = 724067100. Its totient is φ = 718703104.

The previous prime is 721385099. The next prime is 721385111. The reversal of 721385101 is 101583127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 33582025 + 687803076 = 5795^2 + 26226^2 .

It is a cyclic number.

It is not a de Polignac number, because 721385101 - 2¹ = 721385099 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721385101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721385111) 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, 1340596 + ... + 1341133.

It is an arithmetic number, because the mean of its divisors is an integer number (181016775).

Almost surely, 2^721385101 is an apocalyptic number.

It is an amenable number.

721385101 is a deficient number, since it is larger than the sum of its proper divisors (2681999).

721385101 is a wasteful number, since it uses less digits than its factorization.

721385101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2681998.

The product of its (nonzero) digits is 1680, while the sum is 28.

The square root of 721385101 is about 26858.6131622614. The cubic root of 721385101 is about 896.8553217259.

The spelling of 721385101 in words is "seven hundred twenty-one million, three hundred eighty-five thousand, one hundred one".