666951081 has 16 divisors (see below), whose sum is σ = 918650880. Its totient is φ = 429964560.

The previous prime is 666951071. The next prime is 666951097. The reversal of 666951081 is 180159666.

It is a happy number.

It is not a de Polignac number, because 666951081 - 2⁵ = 666951049 is a prime.

It is a super-2 number, since 2×666951081² = 889647488894137122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (666951001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 206626 + ... + 209828.

It is an arithmetic number, because the mean of its divisors is an integer number (57415680).

Almost surely, 2^666951081 is an apocalyptic number.

It is an amenable number.

666951081 is a deficient number, since it is larger than the sum of its proper divisors (251699799).

666951081 is a wasteful number, since it uses less digits than its factorization.

666951081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5476.

The product of its (nonzero) digits is 77760, while the sum is 42.

The square root of 666951081 is about 25825.3960473020. The cubic root of 666951081 is about 873.7046764769.

It can be divided in two parts, 66695 and 1081, that added together give a palindrome (67776).

The spelling of 666951081 in words is "six hundred sixty-six million, nine hundred fifty-one thousand, eighty-one".