215007765721 has 16 divisors (see below), whose sum is σ = 260752665600. Its totient is φ = 173291860368.

The previous prime is 215007765649. The next prime is 215007765733. The reversal of 215007765721 is 127567700512.

215007765721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 215007765721 - 2⁷ = 215007765593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (215007765751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11307891 + ... + 11326888.

It is an arithmetic number, because the mean of its divisors is an integer number (16297041600).

Almost surely, 2^215007765721 is an apocalyptic number.

It is an amenable number.

215007765721 is a deficient number, since it is larger than the sum of its proper divisors (45744899879).

215007765721 is a wasteful number, since it uses less digits than its factorization.

215007765721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22634868.

The product of its (nonzero) digits is 205800, while the sum is 43.

The spelling of 215007765721 in words is "two hundred fifteen billion, seven million, seven hundred sixty-five thousand, seven hundred twenty-one".