402640643 has 4 divisors (see below), whose sum is σ = 407737440. Its totient is φ = 397543848.

The previous prime is 402640633. The next prime is 402640657. The reversal of 402640643 is 346046204.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 402640643 - 2¹⁰ = 402639619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (402640613) 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, 2548280 + ... + 2548437.

It is an arithmetic number, because the mean of its divisors is an integer number (101934360).

Almost surely, 2^402640643 is an apocalyptic number.

402640643 is a deficient number, since it is larger than the sum of its proper divisors (5096797).

402640643 is an equidigital number, since it uses as much as digits as its factorization.

402640643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5096796.

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 402640643 is about 20065.9074801017. The cubic root of 402640643 is about 738.4241135411.

Adding to 402640643 its reverse (346046204), we get a palindrome (748686847).

The spelling of 402640643 in words is "four hundred two million, six hundred forty thousand, six hundred forty-three".