216572721 has 16 divisors (see below), whose sum is σ = 292051200. Its totient is φ = 142747920.

The previous prime is 216572717. The next prime is 216572767. The reversal of 216572721 is 127275612.

It is not a de Polignac number, because 216572721 - 2² = 216572717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216572711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 102130 + ... + 104228.

It is an arithmetic number, because the mean of its divisors is an integer number (18253200).

Almost surely, 2^216572721 is an apocalyptic number.

It is an amenable number.

216572721 is a deficient number, since it is larger than the sum of its proper divisors (75478479).

216572721 is a wasteful number, since it uses less digits than its factorization.

216572721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2476.

The product of its digits is 11760, while the sum is 33.

The square root of 216572721 is about 14716.4099222603. The cubic root of 216572721 is about 600.5298292195.

The spelling of 216572721 in words is "two hundred sixteen million, five hundred seventy-two thousand, seven hundred twenty-one".