721101621 has 16 divisors (see below), whose sum is σ = 988668800. Its totient is φ = 467166528.

The previous prime is 721101613. The next prime is 721101649. The reversal of 721101621 is 126101127.

It is a happy number.

It is not a de Polignac number, because 721101621 - 2³ = 721101613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721101611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 98475 + ... + 105543.

It is an arithmetic number, because the mean of its divisors is an integer number (61791800).

Almost surely, 2^721101621 is an apocalyptic number.

It is an amenable number.

721101621 is a deficient number, since it is larger than the sum of its proper divisors (267567179).

721101621 is a wasteful number, since it uses less digits than its factorization.

721101621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8028.

The product of its (nonzero) digits is 168, while the sum is 21.

The square root of 721101621 is about 26853.3353794273. The cubic root of 721101621 is about 896.7378283758.

Adding to 721101621 its reverse (126101127), we get a palindrome (847202748).

The spelling of 721101621 in words is "seven hundred twenty-one million, one hundred one thousand, six hundred twenty-one".