666110721 has 16 divisors (see below), whose sum is σ = 956637440. Its totient is φ = 410916240.

The previous prime is 666110719. The next prime is 666110771. The reversal of 666110721 is 127011666.

It is not a de Polignac number, because 666110721 - 2¹ = 666110719 is a prime.

It is a super-2 number, since 2×666110721² = 887406985262279682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666110701) 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, 133435 + ... + 138336.

It is an arithmetic number, because the mean of its divisors is an integer number (59789840).

Almost surely, 2^666110721 is an apocalyptic number.

It is an amenable number.

666110721 is a deficient number, since it is larger than the sum of its proper divisors (290526719).

666110721 is a wasteful number, since it uses less digits than its factorization.

666110721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271836.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 666110721 is about 25809.1208877792. The cubic root of 666110721 is about 873.3375655675.

The spelling of 666110721 in words is "six hundred sixty-six million, one hundred ten thousand, seven hundred twenty-one".