265815821 has 2 divisors, whose sum is σ = 265815822. Its totient is φ = 265815820.

The previous prime is 265815799. The next prime is 265815863. The reversal of 265815821 is 128518562.

265815821 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., 249324100 + 16491721 = 15790^2 + 4061^2 .

It is a cyclic number.

It is not a de Polignac number, because 265815821 - 2¹⁸ = 265553677 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (265815521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 132907910 + 132907911.

It is an arithmetic number, because the mean of its divisors is an integer number (132907911).

Almost surely, 2^265815821 is an apocalyptic number.

It is an amenable number.

265815821 is a deficient number, since it is larger than the sum of its proper divisors (1).

265815821 is an equidigital number, since it uses as much as digits as its factorization.

265815821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38400, while the sum is 38.

The square root of 265815821 is about 16303.8590830515. The cubic root of 265815821 is about 642.9742916499.

The spelling of 265815821 in words is "two hundred sixty-five million, eight hundred fifteen thousand, eight hundred twenty-one".