266721857 has 12 divisors (see below), whose sum is σ = 284610060. Its totient is φ = 249954944.

The previous prime is 266721853. The next prime is 266721881. The reversal of 266721857 is 758127662.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 6 ways, for example, as 18627856 + 248094001 = 4316^2 + 15751^2 .

It is not a de Polignac number, because 266721857 - 2² = 266721853 is a prime.

It is a super-2 number, since 2×266721857² = 142281098003056898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (266721853) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1144613 + ... + 1144845.

It is an arithmetic number, because the mean of its divisors is an integer number (23717505).

Almost surely, 2^266721857 is an apocalyptic number.

It is an amenable number.

266721857 is a deficient number, since it is larger than the sum of its proper divisors (17888203).

266721857 is an frugal number, since it uses more digits than its factorization.

266721857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 517 (or 250 counting only the distinct ones).

The product of its digits is 282240, while the sum is 44.

The square root of 266721857 is about 16331.6213830716. The cubic root of 266721857 is about 643.7039914082.

The spelling of 266721857 in words is "two hundred sixty-six million, seven hundred twenty-one thousand, eight hundred fifty-seven".