400003666 has 4 divisors (see below), whose sum is σ = 600005502. Its totient is φ = 200001832.

The previous prime is 400003663. The next prime is 400003679. The reversal of 400003666 is 666300004.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 363703041 + 36300625 = 19071^2 + 6025^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 400003666.

It is not an unprimeable number, because it can be changed into a prime (400003661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100000915 + ... + 100000918.

Almost surely, 2^400003666 is an apocalyptic number.

400003666 is a deficient number, since it is larger than the sum of its proper divisors (200001836).

400003666 is a wasteful number, since it uses less digits than its factorization.

400003666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200001835.

The product of its (nonzero) digits is 2592, while the sum is 25.

The square root of 400003666 is about 20000.0916497900. The cubic root of 400003666 is about 736.8085506644.

The spelling of 400003666 in words is "four hundred million, three thousand, six hundred sixty-six".