83815721 has 8 divisors (see below), whose sum is σ = 92042688. Its totient is φ = 75690000.

The previous prime is 83815717. The next prime is 83815757. The reversal of 83815721 is 12751838.

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 83815721 - 2² = 83815717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (83815621) 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 7 ways as a sum of consecutive naturals, for example, 23570 + ... + 26891.

It is an arithmetic number, because the mean of its divisors is an integer number (11505336).

Almost surely, 2^83815721 is an apocalyptic number.

It is an amenable number.

83815721 is a deficient number, since it is larger than the sum of its proper divisors (8226967).

83815721 is a wasteful number, since it uses less digits than its factorization.

83815721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50623.

The product of its digits is 13440, while the sum is 35.

The square root of 83815721 is about 9155.0926265112. The cubic root of 83815721 is about 437.6314202195.

The spelling of 83815721 in words is "eighty-three million, eight hundred fifteen thousand, seven hundred twenty-one".