644583781402 has 32 divisors (see below), whose sum is σ = 1059586499520. Its totient is φ = 291656177280.

The previous prime is 644583781393. The next prime is 644583781433. The reversal of 644583781402 is 204187385446.

It is a self number, because there is not a number n which added to its sum of digits gives 644583781402.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36148813 + ... + 36166639.

It is an arithmetic number, because the mean of its divisors is an integer number (33112078110).

Almost surely, 2^644583781402 is an apocalyptic number.

644583781402 is a deficient number, since it is larger than the sum of its proper divisors (415002718118).

644583781402 is a wasteful number, since it uses less digits than its factorization.

644583781402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25246.

The product of its (nonzero) digits is 5160960, while the sum is 52.

The spelling of 644583781402 in words is "six hundred forty-four billion, five hundred eighty-three million, seven hundred eighty-one thousand, four hundred two".