265815721 has 2 divisors, whose sum is σ = 265815722. Its totient is φ = 265815720.

The previous prime is 265815701. The next prime is 265815749. The reversal of 265815721 is 127518562.

265815721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 195440400 + 70375321 = 13980^2 + 8389^2 .

It is a cyclic number.

It is not a de Polignac number, because 265815721 - 2¹¹ = 265813673 is a prime.

It is not a weakly prime, because it can be changed into another prime (265815701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 132907860 + 132907861.

It is an arithmetic number, because the mean of its divisors is an integer number (132907861).

Almost surely, 2^265815721 is an apocalyptic number.

It is an amenable number.

265815721 is a deficient number, since it is larger than the sum of its proper divisors (1).

265815721 is an equidigital number, since it uses as much as digits as its factorization.

265815721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 33600, while the sum is 37.

The square root of 265815721 is about 16303.8560162926. The cubic root of 265815721 is about 642.9742110209.

The spelling of 265815721 in words is "two hundred sixty-five million, eight hundred fifteen thousand, seven hundred twenty-one".