666405737 has 4 divisors (see below), whose sum is σ = 672633936. Its totient is φ = 660177540.

The previous prime is 666405689. The next prime is 666405757. The reversal of 666405737 is 737504666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 737504666 = 2 ⋅368752333.

It is a cyclic number.

It is not a de Polignac number, because 666405737 - 2²⁴ = 649628521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666405757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3113939 + ... + 3114152.

It is an arithmetic number, because the mean of its divisors is an integer number (168158484).

Almost surely, 2^666405737 is an apocalyptic number.

It is an amenable number.

666405737 is a deficient number, since it is larger than the sum of its proper divisors (6228199).

666405737 is a wasteful number, since it uses less digits than its factorization.

666405737 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6228198.

The product of its (nonzero) digits is 635040, while the sum is 44.

The square root of 666405737 is about 25814.8355989342. The cubic root of 666405737 is about 873.4664783341.

The spelling of 666405737 in words is "six hundred sixty-six million, four hundred five thousand, seven hundred thirty-seven".