72420721 has 8 divisors (see below), whose sum is σ = 75697344. Its totient is φ = 69154800.

The previous prime is 72420713. The next prime is 72420791. The reversal of 72420721 is 12702427.

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 72420721 - 2³ = 72420713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72420701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13246 + ... + 17896.

It is an arithmetic number, because the mean of its divisors is an integer number (9462168).

Almost surely, 2^72420721 is an apocalyptic number.

It is an amenable number.

72420721 is a deficient number, since it is larger than the sum of its proper divisors (3276623).

72420721 is a wasteful number, since it uses less digits than its factorization.

72420721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5351.

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 72420721 is about 8510.0364864083. The cubic root of 72420721 is about 416.8255015416.

The spelling of 72420721 in words is "seventy-two million, four hundred twenty thousand, seven hundred twenty-one".