215040745721 has 2 divisors, whose sum is σ = 215040745722. Its totient is φ = 215040745720.

The previous prime is 215040745691. The next prime is 215040745729. The reversal of 215040745721 is 127547040512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147667275625 + 67373470096 = 384275^2 + 259564^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215040745721 is a prime.

It is not a weakly prime, because it can be changed into another prime (215040745729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107520372860 + 107520372861.

It is an arithmetic number, because the mean of its divisors is an integer number (107520372861).

Almost surely, 2^215040745721 is an apocalyptic number.

It is an amenable number.

215040745721 is a deficient number, since it is larger than the sum of its proper divisors (1).

215040745721 is an equidigital number, since it uses as much as digits as its factorization.

215040745721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 78400, while the sum is 38.

The spelling of 215040745721 in words is "two hundred fifteen billion, forty million, seven hundred forty-five thousand, seven hundred twenty-one".