647666101 has 4 divisors (see below), whose sum is σ = 647853772. Its totient is φ = 647478432.

The previous prime is 647666099. The next prime is 647666113. The reversal of 647666101 is 101666746.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 541679076 + 105987025 = 23274^2 + 10295^2 .

It is a cyclic number.

It is not a de Polignac number, because 647666101 - 2¹ = 647666099 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (647666401) 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, 88560 + ... + 95593.

It is an arithmetic number, because the mean of its divisors is an integer number (161963443).

Almost surely, 2^647666101 is an apocalyptic number.

It is an amenable number.

647666101 is a deficient number, since it is larger than the sum of its proper divisors (187671).

647666101 is a wasteful number, since it uses less digits than its factorization.

647666101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187670.

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 647666101 is about 25449.2848818980. The cubic root of 647666101 is about 865.2010852628.

The spelling of 647666101 in words is "six hundred forty-seven million, six hundred sixty-six thousand, one hundred one".