402640668 has 36 divisors (see below), whose sum is σ = 1062039888. Its totient is φ = 128377920.

The previous prime is 402640661. The next prime is 402640709. The reversal of 402640668 is 866046204.

It is a happy number.

402640668 is a `hidden beast` number, since 4 + 0 + 2 + 640 + 6 + 6 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402640661) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 242313 + ... + 243968.

It is an arithmetic number, because the mean of its divisors is an integer number (29501108).

Almost surely, 2^402640668 is an apocalyptic number.

It is an amenable number.

402640668 is an abundant number, since it is smaller than the sum of its proper divisors (659399220).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

402640668 is a wasteful number, since it uses less digits than its factorization.

402640668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486314 (or 486309 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 402640668 is about 20065.9081030488. The cubic root of 402640668 is about 738.4241288241.

The spelling of 402640668 in words is "four hundred two million, six hundred forty thousand, six hundred sixty-eight".