73215721 has 8 divisors (see below), whose sum is σ = 77184800. Its totient is φ = 69258240.

The previous prime is 73215679. The next prime is 73215743. The reversal of 73215721 is 12751237.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 73215721 - 2¹⁵ = 73182953 is a prime.

It is a super-3 number, since 3×73215721³ (a number of 25 digits) contains 333 as substring.

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 73215721.

It is not an unprimeable number, because it can be changed into a prime (73215421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12106 + ... + 17116.

It is an arithmetic number, because the mean of its divisors is an integer number (9648100).

Almost surely, 2^73215721 is an apocalyptic number.

It is an amenable number.

73215721 is a deficient number, since it is larger than the sum of its proper divisors (3969079).

73215721 is a wasteful number, since it uses less digits than its factorization.

73215721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5799.

The product of its digits is 2940, while the sum is 28.

The square root of 73215721 is about 8556.6185494037. The cubic root of 73215721 is about 418.3451911511.

Adding to 73215721 its reverse (12751237), we get a palindrome (85966958).

The spelling of 73215721 in words is "seventy-three million, two hundred fifteen thousand, seven hundred twenty-one".