666474671641 has 9 divisors (see below), whose sum is σ = 690273556063. Its totient is φ = 643469927800.

The previous prime is 666474671627. The next prime is 666474671657. The reversal of 666474671641 is 146176474666.

The square root of 666474671641 is 816379.

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., 349483151241 + 316991520400 = 591171^2 + 563020^2 .

It is not a de Polignac number, because 666474671641 - 2¹⁷ = 666474540569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666474671441) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 23660916 + ... + 23689066.

Almost surely, 2^666474671641 is an apocalyptic number.

666474671641 is the 816379-th square number.

666474671641 is the 408190-th centered octagonal number.

It is an amenable number.

666474671641 is a deficient number, since it is larger than the sum of its proper divisors (23798884422).

666474671641 is an frugal number, since it uses more digits than its factorization.

666474671641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56360 (or 28180 counting only the distinct ones).

The product of its digits is 24385536, while the sum is 58.

The spelling of 666474671641 in words is "six hundred sixty-six billion, four hundred seventy-four million, six hundred seventy-one thousand, six hundred forty-one".