265265171521 has 45 divisors (see below), whose sum is σ = 324206705571. Its totient is φ = 217008592416.

The previous prime is 265265171513. The next prime is 265265171539. The reversal of 265265171521 is 125171562562.

The square root of 265265171521 is 515039.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 229417050625 + 35848120896 = 478975^2 + 189336^2 .

It is not a de Polignac number, because 265265171521 - 2³ = 265265171513 is a prime.

It is a super-2 number, since 2×265265171521² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (265265171581) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 580448725 + ... + 580449181.

Almost surely, 2^265265171521 is an apocalyptic number.

265265171521 is the 515039-th square number.

265265171521 is the 257520-th centered octagonal number.

It is an amenable number.

265265171521 is a deficient number, since it is larger than the sum of its proper divisors (58941534050).

265265171521 is an frugal number, since it uses more digits than its factorization.

265265171521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988 (or 487 counting only the distinct ones).

The product of its digits is 252000, while the sum is 43.

The spelling of 265265171521 in words is "two hundred sixty-five billion, two hundred sixty-five million, one hundred seventy-one thousand, five hundred twenty-one".