666391254722 has 18 divisors (see below), whose sum is σ = 1044978397113. Its totient is φ = 318696161872.

The previous prime is 666391254679. The next prime is 666391254769. The reversal of 666391254722 is 227452193666.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 635972755441 + 30418499281 = 797479^2 + 174409^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=577231.

It is a super-2 number, since 2×666391254722² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 26540078 + ... + 26565174.

Almost surely, 2^666391254722 is an apocalyptic number.

666391254722 is a deficient number, since it is larger than the sum of its proper divisors (378587142391).

666391254722 is an frugal number, since it uses more digits than its factorization.

666391254722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50242 (or 25122 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 53.

The spelling of 666391254722 in words is "six hundred sixty-six billion, three hundred ninety-one million, two hundred fifty-four thousand, seven hundred twenty-two".